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How to Write a Literature Review | Guide, Examples, & Templates

Published on January 2, 2023 by Shona McCombes . Revised on September 11, 2023.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research that you can later apply to your paper, thesis, or dissertation topic .

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates, and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarize sources—it analyzes, synthesizes , and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

What is the purpose of a literature review, examples of literature reviews, step 1 – search for relevant literature, step 2 – evaluate and select sources, step 3 – identify themes, debates, and gaps, step 4 – outline your literature review’s structure, step 5 – write your literature review, free lecture slides, other interesting articles, frequently asked questions, introduction.

• Quick Run-through
• Step 1 & 2

When you write a thesis , dissertation , or research paper , you will likely have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and its scholarly context
• Develop a theoretical framework and methodology for your research
• Position your work in relation to other researchers and theorists
• Show how your research addresses a gap or contributes to a debate
• Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic.

Writing literature reviews is a particularly important skill if you want to apply for graduate school or pursue a career in research. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research problem and questions .

Make a list of keywords

Start by creating a list of keywords related to your research question. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list as you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some useful databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can also use boolean operators to help narrow down your search.

Make sure to read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

You likely won’t be able to read absolutely everything that has been written on your topic, so it will be necessary to evaluate which sources are most relevant to your research question.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models, and methods?
• Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible , and make sure you read any landmark studies and major theories in your field of research.

You can use our template to summarize and evaluate sources you’re thinking about using. Click on either button below to download.

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It is important to keep track of your sources with citations to avoid plagiarism . It can be helpful to make an annotated bibliography , where you compile full citation information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

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To begin organizing your literature review’s argument and structure, be sure you understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly visual platforms like Instagram and Snapchat—this is a gap that you could address in your own research.

There are various approaches to organizing the body of a literature review. Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarizing sources in order.

Try to analyze patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organize your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text , your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, you can follow these tips:

• Summarize and synthesize: give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: don’t just paraphrase other researchers — add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically evaluate: mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: use transition words and topic sentences to draw connections, comparisons and contrasts

In the conclusion, you should summarize the key findings you have taken from the literature and emphasize their significance.

When you’ve finished writing and revising your literature review, don’t forget to proofread thoroughly before submitting. Not a language expert? Check out Scribbr’s professional proofreading services !

This article has been adapted into lecture slides that you can use to teach your students about writing a literature review.

Scribbr slides are free to use, customize, and distribute for educational purposes.

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If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

• Sampling methods
• Simple random sampling
• Stratified sampling
• Cluster sampling
• Likert scales
• Reproducibility

 Statistics

• Null hypothesis
• Statistical power
• Probability distribution
• Effect size
• Poisson distribution

Research bias

• Optimism bias
• Cognitive bias
• Implicit bias
• Hawthorne effect
• Anchoring bias
• Explicit bias

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarize yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your thesis or dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

How To Find A-Grade Literature For Review

Sourcing, evaluating and organising.

By: David Phair (PhD) and Peter Quella (PhD) | January 2022

As we’ve discussed previously on our blog and YouTube channel, the first step of the literature review process is to source high-quality , relevant resources for your review, and to catalogue these pieces of literature in a systematic way so that you can digest and synthesise all the content efficiently.

In this article, we’ll look discuss 6 important things to keep in mind for the initial stage of your literature review so that you can source high-quality, relevant resources, quickly and efficiently. Let’s get started!

Overview: Literature Review Sourcing

• Develop and follow a clear literature search strategy
• Understand and use different types of literature correctly
• Carefully evaluate the quality of your potential sources
• Use a reference manager and a literature catalogue
• Read as broadly and comprehensively as possible
• Keep your golden thread front of mind throughout the process

1. Have a clear literature search strategy

As with any task in the research process, you need to have a clear plan of action before you get started, or you’ll end up wasting a lot of time and energy. So, before you begin your literature review , it’s useful to develop a simple search strategy . Broadly speaking, a good literature search strategy should include the following steps:

Step one – Clearly identify your golden thread

Your golden thread consists of your research aims , research objectives and research questions . These three components should be tightly aligned to form the focus of your research. If you’re unclear what your research aims and research questions are, you’re not going to have a clear direction when trying to source literature. As a result, you’re going to waste a lot of time reviewing irrelevant resources.

So, make sure that you have clarity regarding your golden thread before you start searching for literature. Of course, your research aims, objectives and questions may evolve or shift as a result of the literature review process (in fact, this is quite common), but you still need to have a clear focus to get things started.

Step two – Develop a keyword/keyphrase list

Once you’ve clearly articulated your golden thread in terms of the research aims, objectives and questions, the next step is to develop a list of keywords or keyphrases, based on these three elements (the golden thread). You’ll also want to include synonyms and alternative spellings (for example, American vs British English) in your list.

For example, if your research aims and research questions involve investigating organisational trust , your keyword list might include:

• Organisational trust
• Organizational trust (US spelling)
• Consumer trust
• Brand trust
• Online trust

When it comes to brainstorming keywords, the more the better . Don’t hold back at this stage. You’ll quickly find out which ones are useful, and which aren’t when you start searching. So, it’s best to just go as broad as possible here to ensure you cast a wide net.

Step three – Identify the relevant databases

Now that you’ve got a comprehensive set of keywords, the next step is to identify which literature databases will be most useful and relevant for your particular study. There are hundreds, if not thousands of databases out there, and they are often subject or discipline-specific . For example, within the medicine space, Medline is a popular one.

To identify relevant databases, it’s best to speak to your research advisor/supervisor, Grad Coach or a librarian at your university library. Oftentimes, a quick chat with a skilled librarian can yield tremendous insight. Don’t be shy to ask – chances are, they’ll be thrilled that you asked!

At this stage, you might be asking, “why not just use Google Scholar?”. Of course, an academic search engine like Google Scholar will be useful in terms of getting started and finding a broad range of resources, but it won’t always present every possible resource  or the best quality resources. It also has limited filtering options compared to some of the specialist databases, so you shouldn’t rely purely on Google Scholar.

Step four – Use Boolean operators to refine your search

Once you’ve identified your keywords and databases, it’s time to start searching for literature – hooray! However, you’ll quickly find that there is a seemingly endless number of journal articles to sift through, and you have limited time to work through the literature. So, you’ll need to get smart about how you use these databases – enter Boolean operators.

Boolean operators are special characters that allow you to refine your search. Common operators include:

• AND – only show results that contain both X and Y
• OR – show results that contain X or Y
• NOT – show results that include X, but not Y

These operators are incredibly useful, especially when there are topics that are very similar to yours but are not relevant . For example, if you’re researching something about the growth of apples, you’ll want to exclude all literature related to Apple, the company. Boolean operators allow you to cut out the irrelevant content and improve the signal to noise ratio in your search.

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2. Use different types of literature correctly

Once you start searching for literature, you’ll quickly notice that there are different “types” of resources that come up. It’s important to understand the different types of literature available to you and how to use each of them appropriately.

Generally speaking, you’ll find three categories of literature:

Primary literature

Secondary literature

Tertiary literature

Primary literature refers to journal articles , typically peer reviewed, which document a study that was undertaken, where data were collected and analysed, and findings were discussed. For example, a journal article that involves the collection and analysis of survey data to identify differences in personality between two groups of people.

Primary literature should, ideally, form the foundation of your literature review – the bread and butter, so to speak. You’ll likely refer to many of the arguments made and findings identified in these types of articles to build your own arguments throughout your literature review. You’ll also rely on these types of articles for theoretical models and frameworks, which may form the foundation of your own proposed framework, depending on the nature of your research.

Lastly, primary literature can be a useful source of measurement scales for quantitative studies. For example, many journal articles will include a copy of the survey measures they used at the end of the article, which will typically be reliable and valid. You can either use these “as is” or as a foundation for your own survey measures .

So, long story short, you’ll need a good stockpile of these types of resources. They are, admittedly, more “dense” and challenging to digest than the other types of literature, but taking the time to work through them will pay off greatly.

Secondary literature refers to journal articles that summarise and integrate the findings from primary literature. For example, you’ll likely find “review of the literature” type journal articles which provide an overview of the current state of the research (at the time of publication, of course).

Secondary literature is very useful for orienting yourself with regards to the current state of knowledge and identifying key researchers , seminal works and so on. In other words, they’re a good tool to make sure you’ve got a broad, comprehensive view of what all is out there. They’re not going to give you the level of detail that primary literature will (and they’ll likely be a bit outdated), but they’ll point you in the right direction.

In practical terms, it’s a good idea to start by reviewing secondary literature-type articles to help you get a bird’s eye view of the landscape and then dive deeper into the primary literature to get a grasp of the specifics and to bring your knowledge up to date with the most current studies.

The final category of literature refers to sources that would be considered less academic and scientifically rigorous in nature, but up to date and highly relevant. For example, sources such as current industry and country reports published by management consulting groups, news articles, blog posts and so on.

While these sources are not as credible and trustworthy as journal articles (especially peer-reviewed ones), they can provide very up to date information , whereas academic research tends to roll out quite slowly. Therefore, they can be very useful for contextualising your research topic and/or demonstrating a current trend. Quite often, you’d cite these types of sources in your introduction chapter rather than your literature review chapter, but you may still have use for them in the latter.

In summary, it’s important to understand the three different types of literature – primary, secondary and tertiary, and use them appropriately in your dissertation, thesis or research project.

3. Carefully evaluate the quality of your sources

As we’ve alluded to, not all literature is created equally. Not only does literature vary in terms of type (i.e., primary vs secondary), it also varies in terms of overall quality .

Simply put, all sources exist on a quality spectrum . On the high end of the spectrum are peer-reviewed articles published in popular, credible journals. Next are journal articles that are not peer-reviewed, or that are published in lower quality or lesser-known journals. In the middle are sources like textbooks and reports by professional organisations (e.g., management consulting firms). On the low end are sources like newspapers, blog posts and social media posts.

As you can probably see, this loosely reflects the categories we mentioned previously (primary, secondary and tertiary literature), so there is once again a trade-off between quality and recency . Therefore, you need to carefully evaluate the quality of each potential source and let this inform how you use it in your literature review. Importantly, this doesn’t mean that you can’t include a newspaper article or blog post as a source – it just means that you shouldn’t rely too heavily on these types of courses as the core of your argument.

When evaluating journal articles, you can consider their citation count (i.e., the number of other articles that reference them) as a quality indicator. But keep in mind that citation count is a product of many factors , including the popularity of the article, the popularity of the research field and most importantly, time. In other words, it’s natural for newer articles to have lower citation counts. This is useful to keep in mind, as you ideally want to focus on more recent literature (published within the last 3-5 years) in your literature review.

In summary, aim to focus on higher-quality literature , especially when you’re building core arguments in your literature review. You don’t, for example, want to make an argument regarding the importance and novelty of your research (i.e., its justification) based on some blogger’s opinion.

4. Use a reference manager and literature catalogue

As you review the literature and build your collection of potential sources, you’ll need a way to stay on top of all the details. To this end, it’s essential that you make use of both a reference manager and a literature catalogue . Let’s take a look at each of these.

The reference manager

Reference management software helps you store the reference information for each of your articles and manages the citation and reference list building task as you write up your actual literature review chapter. In other words, a reference manager ensures that your citations and reference list are correctly formatted in the reference style required by your university – e.g., Harvard, APA , MLA, etc.

Using a reference manager saves you the hassle of trying to manually type out your in-text citations and reference list, which you’re bound to mess up in some way. A simple comma out of place, incorrect italicisation or boldfacing can result in you losing marks, and that’s highly likely when you’re dealing with a large number of references. So, it just makes sense to use a piece of software for this task.

The good news is that there are loads of options , many of which are free . For new researchers, we usually recommend Mendeley or Zotero . So, don’t waste your time trying to manage your references manually – get yourself a reference manager ASAP.

The literature catalogue

The second tool you’ll need is a literature catalogue. This is simply an Excel document that you can easily compile yourself (or download our free one here ), where you list and categorise all your literature. You might doubt whether it’s really necessary to have a separate catalogue when you’ve already logged your reference data in a reference manager, but trust us, you’re going to need it. It’s quite common that throughout the literature review process, you’ll review hundreds of articles , so it’s simply impossible that you’ll remember all the details.

What makes a literature catalogue extremely powerful is that you can store as much information as you want for each piece of literature that you include (whereas a reference manager only includes basic fields). Typically, you would include things like:

• Title of the article
• One-line summary of the research
• Key findings and takeaways
• Context (i.e. where did it take place)
• Useful quotes
• Methodology (e.g. qualitative, quantitative or mixed methods)
• Category (you can customise as many categories as makes sense for you)
• Quality of resource
• Type of literature (e.g. primary, secondary or tertiary)

These are just some examples – ultimately you need to customise your catalogue to suit your needs. But, as you can see, the more detailed you get, the more useful your catalogue will become when it’s time to synthesise the research and write up your literature. For example, you could quickly filter the catalogue to display all papers that support a certain hypothesis, that argue in a specific direction, or that were written at a certain time.

5. Read widely (and efficiently)

As we’ve discussed in other posts , the purpose of the literature review chapter is to present and synthesise the current state of knowledge in relation to your research aims, objectives and research questions. To do this, you’ll need to read as broadly and comprehensively as possible. You’ll need to demonstrate to your marker that you “know your stuff” and have a strong understanding of the relevant literature.

Ideally, your literature review should include an eclectic mix of research that features multiple perspectives . In other words, you need to avoid getting tunnel vision and running down one narrow stream of literature. Ideally, you want to highlight both the agreements and disagreements in the literature to show that you’ve got a well-balanced view of the situation.

If your topic is particularly novel and there isn’t a lot of literature available, you can focus your efforts on adjacent literature . For example, if you’re researching factors that cultivate organisational trust in Germany, but there’s very little literature on this, you can draw on US and UK-based studies to form your theoretical foundation. Similarly, if you’re investigating an occurrence in an under-researched industry, you can look at other industries for literature.

As you read each journal article, be sure to scan the reference list for further reading (this technique is called “snowballing”). By doing this, you will quickly identify key literature within a topic area and fast-track your literature review process. You can also check which articles have cited any given article using Google Scholar, which will give you a “forward view” in terms of the progress of the literature.

Given that you’ll need to work through a large amount of literature, it’s useful to adopt a “strategic skimming ” approach when you’re initially assessing articles, so that you don’t need to read the entire journal article . In practical terms, this means you can focus on just the title and abstract at first, and if the article seems relevant based on those, you can jump to the findings section and limitations section . These sections will give you a solid indicator as to whether the resource is relevant to your study, which you can then shortlist for full reading.

6. Keep your golden thread front of mind

Your golden thread (i.e., your research aims, objectives and research questions) needs to guide every decision you make throughout your dissertation, thesis, or research project. This is especially true in the literature review stage, as the golden thread should act as a litmus test for relevance whenever you’re reviewing potential articles or resources. In other words, if an article doesn’t relate to your golden thread, its probably not worth spending time on.

Keep in mind that your research aims, objectives and research questions may evolve as a result of the literature review process. For example, you may find that after reviewing the literature in more depth, your topic focus is not as novel as you originally thought, or that there’s an adjacent area that is more deserving of investigation. This is perfectly natural, so don’t be surprised if your focus shifts somewhat during the review process. Just remember to update your literature review in this case and be sure to update any previous chapters so that your document has a consistent focus throughout.

Wrapping up

In this article, we covered 6 pointers to help you find and evaluate high-quality resources for your literature review. To recap:

• Understand and use different types of literature for the right purpose

If you have any questions, please feel free to leave a comment . Alternatively, if you’d like hands-on help with your literature review, be sure to check out our 1-on-1 private coaching services here.

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

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this is very helpful to any researcher, I am learning this for the benefit of myself and overs as a library staff

Of course this is useful to most of researchers. I have learnt a lot issues which are relevant to teaching research. Surely they will enjoy my research sessions.

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Chapter 4: Where to Find the Literature

Learning objectives.

At the conclusion of this chapter, you will be able to:

• Search a library catalog to locate electronic and print books.
• Search databases to find scholarly articles, dissertations, and conference proceedings.
• Retrieve a copy or the full text of information sources
• Identify and locate core resources in your discipline or topic area

4.1 Overview of discovery

Discovery, or background research, is something that happens at the beginning of the research process when you are just learning about a topic. It is a search for general information to get the big picture of a topic for exploration, ideas about subtopics and context for the actual focused research you will do later. It is also a time to build a list of distinctive, broad, narrow, and related search terms.

Discovery happens again when you are ready to focus in on your research question and begin your own literature review. There are two crucial elements to discovering the literature for your review with the least amount of stress as possible: the places you look and the words you use in your search .

The places you look depend on:

• The stage you are in your research
• The disciplines represented in your research question
• The importance of currency in your research topic

Review the information and publication cycles discussed in Chapter 2 to put those sources of this information in context.

The words you use will help you locate existing literature on your topic, as well as topics that may be closely related to yours. There are two categories for these words:

• Keywords – the natural language terms we think of when we discuss and read about a topic
• Subject terms – the assigned vocabulary for a catalog or database

The words you use during both the initial and next stage of discovery should be recorded in some way throughout the literature search process. Additional terms will come to light as you read and as your question becomes more specific. You will want to keep track of those words and terms, as they will be useful in repeating your searches in additional databases, catalogs, and other repositories. Later in this chapter, we will discuss how putting the two elements (the places we look and the words we use) together can be enhanced by the use of Boolean operators and discipline-specific thesauri.

Discovery is an iterative process. There is not a straight, bright line from beginning to end. You will go back into the literature throughout the writing of your literature review as you uncover gaps in the evidence and as additional questions arise.

4.2 Finding sources: Places to look

Let’s take some time to look at where the information sources you need for your literature review are located, indexed, and stored. At this stage, you have a general idea of your research area and have done some background searching to learn the scope and the context of your topic. You have begun collecting keywords to use in your later searching. Now, as you focus in on your literature review topic, you will take your searches to the databases and other repositories to see what the other researchers and scholars are saying about the topic.

The following resources are ordered from the more general and established information to the more recent and specific. Although it is possible to find some of these resources by searching the open web, using a search engine like Google or Google Scholar, this is not the most efficient or effective way to search for and discover research material. As a result, most of the resources described in this section are found from within academic library catalogs and databases, rather than internet search engines.

4.2.1 Finding books and ebooks

4.2.1.1 books.

Look to books for broad and general information that is useful for background research. Books are “essential guides to understanding theory and for helping you to validate the need for your study, confirm your choice of literature, and certify (or contradict) its findings.” ( Fink, 4th ed., 2014, p. 77 ). In this section, we will consider print and electronic books as well as print and electronic encyclopedias.

Most academic libraries use the Library of Congress classification system to organize their books and other resources. The Library of Congress classification system divides a library’s collection into 21 classes or categories. A specific letter of the alphabet is assigned to each class. More detailed divisions are accomplished with two and three letter combinations. Book shelves in most academic libraries are marked with a Library of Congress letter-number combination to correspond to the Library of Congress letter-number combination on the spines of library materials. This is often referred to as a call number and it is noted in the catalog record of every physical item on the library shelves. ( Bennard et al, 2014a )

The Library of Congress (LC) classification for Education (General) is L7-991, with LA, LB, LC, LD, LE, LG, LH, LJ, and LT subclasses. For example,

LB3012.2.L36 1995 Beyond the Schoolhouse Gate: Free Speech and the Inculcation of Values

In Nursing, the LC subject range is RT1-120. A book with this LC call number might look like: R121.S8 1990 Stedman’s Medical Dictionary . Areas related to nursing that are outside that range include:

R121 Medical dictionaries

R726.8 Hospice care

R858-859.7 Medical informatics

RB37 Diagnostic and laboratory tests

RB115 Nomenclature (procedural coding – CPT, ICD9)

RC69-71 Diagnosis

RC86.7 Emergency medicine

RC266 Oncology nursing

RC952-954.6 Geriatrics

RD93-98 Wound care

RD753 Orthopedic nursing

RG951 Maternal child nursing / Obstetrical nursing

RJ245 Pediatric nursing

RM216 Nutrition and diet therapy

RM301.12 Drug guides

In most libraries, there is a collection of reference material kept in a specific section. These books, consisting of encyclopedias, dictionaries, thesauri, handbooks, atlases, and other material contain useful background or overview information about topics. Ask the librarian for help in finding an appropriate reference book. Although reference material can only be used in the library, other print books will likely be in what’s called the “circulating collection,” meaning they are available to check out.

4.2.1.2 Ebooks

The library also provides access to electronic reference material. Some are subject specific and others are general reference sources. Although each resource will have a different “look” just as different print encyclopedias and dictionaries look different, each should have a search box. Most will have a table of contents for navigation within the work. Content includes pages of text in books and encyclopedias and occasionally, videos. In all cases you will be able to collect background information and search terms to use later.

North American academic libraries buy or subscribe to individual ebook titles as well as collections of ebooks. Ebooks appear on various publisher and platforms, such as Springer, Cambridge, ebrary (ProQuest), EBSCO, and Safari to name a few. Although access to these ebooks varies by platform, you can find the ebook titles your library has access to through the library catalog. You can generally read the entire book online, and you can often download single chapters or a limited number of pages. You may be able to download an entire ebook without restrictions, or you may have to ‘check it out’ for a limited period of time. Some downloads will be in PDF format, others use another type of free ebook viewing software, like ePUB. Unlike public library ebook collections, most academic library ebooks are not be downloadable to ereader devices, such as Amazon’s Kindle

4.2.1.3 The Library Catalog

In general, everything owned or licensed by a library is indexed in “the library catalog”. Although most library catalogs are now sophisticated electronic products called ‘integrated library systems’, they began as wooden card filing cabinets where researchers could look for books by author, title, or subject.

While the look and feel of current integrated library systems vary between libraries, they operate in similar ways. Most library catalogs are quickly found from a library’s home page or website. The library catalog is the quickest way to find books and ebooks on your topic.

Here are some general tips for locating books in a library catalog:

• Use the search box generally found on a library’s home page to start a search.
• Type a book title, author name, or subject keywords into the search box.
• You will be directed to a results page.
• If you click on a book title or see an option to see more details about the book, you can look at its full bibliographic record, which provides more information about the book, as well as where to find the book. Pay particular attention to subjects associated with the item, adding relevant and appropriate terms to your list of search terms for future use.
• Look for an “Advanced Search” option near the basic or single search box
• Publication Year
• Call number
• There is generally a “Format” list on the advanced search page screen. This list will give you options for limiting format to Print Books or Ebooks.
• You can limit searches to a specific library or libraries to narrow by location or ‘search everything’ to broaden your search.

OCLC WorldCat ( https://www.worldcat.org/ ) is the world’s largest network of library content and it provides another way to search for books and ebooks. For students who do not have immediate access to an academic library catalog, WorldCat is a way to search many library catalogs at once for an item and then locate a library near you that may own or subscribe to it. Whether you will be able check the item out, request it, place an interlibrary loan request for it, or have it shipped will depend on local library policy. Note that like your own library catalog, WorldCat has a single search box, an Advanced search feature, and a way to limit by format and location.

4.2.2 Finding scholarly articles

While books and ebooks provide good background information on your topic, the main body of the literature in your research area will be found in academic journals. Scholarly journals are the main forum for research publication. Unlike books and professional magazines that may comment or summarize research findings, articles in scholarly journals are written by a researcher or research team. These authors will report in detail original study findings, and will include the data used. Articles in academic journals also go through a screening or peer-review process before publication,implying a higher level of quality and reliability. For the most current, authoritative information on a topic, scholars and researchers look to the published, scholarly literature. That said,

Journals, and the articles they contain, are often quite expensive. Libraries spend a large part of their collection budget subscribing to journals in both print and online formats. You may have noticed that a Google Scholar search will provide the citation to a journal article but will not link to the full text. This happens because Google does not subscribe to journals. It only searches and retrieves freely available web content. However, libraries do subscribe to journals and have entered into agreements to share their journal and book collections with other libraries. If you are affiliated with a library as a student, staff, or faculty member, you have access to many other libraries’ resources, through a service called interlibrary loan. Do not pay the large sums required to purchase access to articles unless you do not have another way to obtain the material, and you are unable to find a substitute resource that provides the information you need. ( Bennard et al, 2014 a)

4.2.2.1 Databases

A database is an electronic system for organizing information. Journal databases are where the scholarly articles are organized and indexed for searching. Anyone with an internet connection has free access to public databases such as PubMed and ERIC. Students can also search in library-subscribed general information databases (such as EBSCO’s Academic Search Premier) or a specialized or subject specific database (for example, a ProQuest version of CINAHL for Nursing or ERIC for Education).

Library databases store and display different types of information sets than a library catalog or Google Scholar. There are different types of databases that include:

• Indexes– with citations only
• Abstract databases – with citations and abstracts only
• Full text databases – with citations and the full text of articles, reports, and other materials

Library databases are often connected to each other by means of a “link resolver”, allowing different databases to “talk to each other.” For example, if you are searching an index database and discover an article you want to read in its entirety, you can click on a link resolver that takes you to another database where the full-text of the article is held. If the full-text is not available, an automated form to request the item from another library may be an option.

Why search a database instead of Google Scholar or your library catalog? Both can lead you to good articles BUT:

• The content is wide-ranging but not comprehensive or as current as a database that may be updated daily.
• Google Scholar doesn’t disclose its criteria for what makes the results “scholarly’ and search results often vary in quality and availability.
• Neither gives you as much control over your search as you get in a database.

4.2.2.2 Citation searches

Another way to find additional books and articles on your topic is to mine the reference lists of books and articles you already found. By tracing literature cited in published titles, you not only add to your understanding of the scholarly conversation about your research topic but also enrich your own literature search.

A citation is a reference to an item that gives enough information for you to identify it and find it again if necessary. You can use the citations in the material you found to lead you to other resources. Generally, citations include four elements:

For example,

For a good summary of how to read a citation for a book, book chapter, and journal article in both APA and MLA format, see this explanation   at: https://www.slideshare.net/opensunytextbooks/gathering-components-of-a-citation

4.2.3 Finding conference papers

Conference papers are often overlooked because they can be difficult to locate in full-text. Sometimes the papers from an annual proceeding are treated like an individual book, or a single special issue of a journal. Sometimes the papers from a conference are not published and must be requested from the original author. Despite publication inconsistency, conference papers may be the first place a scholar presents important findings and, as such, are relevant to your own research. Places to look for conference papers:

4.2.3.1 WorldCat

• use keywords from the conference name (NOT the article title)
• it often helps to leave out terms like: conference, proceedings, transactions, congresses, symposia/symposium, exposition, workshop or meeting
• include the year of the conference
• include the city in which the conference took place

4.2.3.2 Google Scholar

• Search by keyword and add the word ‘conference’ and the year to your search, for example: ‘conference education 2008′

4.2.3.3 Databases

• For Education: ERIC, limit to ‘Collected Works–Proceedings’ or ‘Speeches/Meeting papers’
• For Nursing: CINAHL, limit to proceedings in the “Publication Type” box
• For Education: Education Full Text, limit to ‘proceeding’ in the “Document Type” box
• PsychInfo: limit to ‘Conference Proceedings’ in the “Record Type” Box
• Web of Science: limit to ‘conference’

4.2.3.4 Professional Societies & Other Sponsoring Organizations

Check the web sites of the organizations that sponsor conferences. Listings of conference proceedings are often under a “Publications” or “Meetings” tab/link. The National Library of Medicine maintains a conference proceedings subject guide for health-related national and international conferences. Though many papers/proceedings are not available for free, the organization web site will often contain citations of proceedings that you can request through interlibrary loan.

4.2.4 Finding dissertations

In addition to journal articles, original research is also published in books, reports, conference proceedings, theses and dissertations. Both theses and dissertations are very detailed and comprehensive accounts of research work. Dissertations and theses are a primary source of original research and include “referencing, both in text and in the reference list, so that, in principle, any reference to the literature may be easily traced and followed up.” ( Wallace & Wray, p. 187 ). Citation searching of the reference list or bibliography in a dissertation is another method for discovering the relevant literature for your own research area. Like conference papers, they are more difficult to locate and retrieve than books and articles. Some may be available electronically in full-text at no cost. Others may only be available to the affiliates of the university or college where a degree was granted. Others are behind paywalls and can only be accessed after purchasing. Both CINAHL and ERIC index dissertations. Individual universities and institutional repositories often list dissertations held locally. Other places to look for theses and dissertations include:

Dissertations Express – search for dissertations from around the world. Search by subject or keyword, results include author, title, date, and where the degree was granted. Some are available in full-text at no cost, however most requirement payment.

EThOS – the national thesis service for the United Kingdom, managed by the British Library. It is a national aggregated record of all doctoral theses awarded by UK Higher Education institutions, providing free access to the full text of many theses for use by all researchers to further their own study.

Theses Canada – a collaborative program between Library and Archives Canada (LAC) and nearly 70 accredited Canadian universities. The collection contains both microfiche and electronic theses and dissertations that are for personal or academic research purposes.

4.3 Advanced searching

Now that you have an idea of some of the places to look for information on your research topic and the form that information takes (books, ebooks, journals, conference papers, and dissertations), it’s time to consider not only how to use the specialized resources for your discipline but how to get the most out of those resources. To do a graduate-level literature review and find everything published on your topic, advanced search and retrieval skills are needed.

4.3.1 Search Operators

Literature review research often necessitates the use of Boolean operators to combine keywords. The operators – AND, OR, and NOT — are powerful tools for searching in a database or search engine. By using a combination of terms and one or more Boolean operator, you can focus your search and narrow your search results to a more specific area than a basic keyword search allows.

Boolean operators – allow you to combine your search terms using the keywords AND , OR and NOT . Look at the diagrams in Figure 4.6 to see how these terms will affect your results.

Truncation – If you use truncation (or wildcards), your search results will contain documents including variations of that term.

For example: light* will retrieve, of course, light , but also terms like: lighting , lightning , lighters and lights . Note that the truncation symbol varies depending on where you search. The most common truncation symbols are the asterisk (*) and question mark (?).

Phrase searching – Phrase searching is used to make sure your search retrieves a specific concept. For example “ durable wood products ” will retrieve more relevant documents than the same terms without quotation marks.

For a description of these more advanced search features, watch this short video tutorial on effective search strategies. ( Clark, 2016 ).

4.3.2 Finding sources in your discipline or topic area

It’s time to put these tips and your search skills to use. This is the point, if you have not done so already, to talk to a librarian. The librarian will direct you to the resources you need, including research databases to which the library subscribes, for your discipline or subject area. Literature reviews rely heavily on data from online databases, such as CINAHL for Nursing and ERIC for Education. Unfortunately, the costs to subscribe to vendor-provided products is high. Students affiliated with large university libraries that can afford to subscribe to these products will have access to many databases, while those who do not have fewer options.

Students who do not have access to subscription databases such as CINAHL or ERIC through Ebsco and ProQuest should use PubMed for Nursing at https://www.ncbi.nlm.nih.gov/pubmed/ and the public version of ERIC at https://eric.ed.gov/ for literature review research.

Although a librarian is the best resource for learning how to use a specific tool, an online tutorial on how to search PubMed may be useful and informative for those who do not have access to a librarian or a subscription database: Likewise, this document, titled “ How does the ERIC search work ,” provided by the Institute of Education Sciences provides some helpful tips for searching the public version ERIC.

4.3.3 Specialized vocabulary

One major source of search terms in a database is a specialized dictionary, or thesaurus, used to index journal articles. Thesauri provide a consistent and standardized way to retrieve information, especially when different terms are used for the same concept. According to Fink ( 2014 ), “evidence exists that using thesaurus terms produces more of the available citations than does reliance on key words…Using the appropriate subject heading will enable the reviewer to find all citations regardless of how the author uses the term.” (p. 24).

In Education and Nursing, thesauri are available. In subscription databases, as well as in PubMed and the public version of ERIC, look for the thesaurus to guide you to appropriate and relevant subject terms.

4.3.4 Citation Searching

Citation searching works best when you already have a relevant work that is on topic. From the document you identified as useful for your own literature review, you can either search citations forward or backward to gather additional resources. Cited reference searching and reference or bibliography mining are advanced search techniques that may also help generate new ideas as well as additional keywords and subject areas.

For cited reference searching, use Google Scholar or library databases such as Web of Science or Scopus. These tools trace citations forward to link to newly published books, journal articles, book chapters, and reports that were written after the document you found. Through cited reference searching, you may also locate works that have been cited numerous times, indicating what may be a seminal work in your field.

With citation mining, you will look at the references or works cited list in the resource you located to identify other relevant works. In this type of search, you will be tracing citations backward to find significant books, journal articles, book chapters, and reports that were written before the document you found. For a brief discussion about citation searching , check out this article by Hammond & Brown ( 2008 ).

The two most important finding tools you will use are a library catalog and databases. Looking for information in catalogs and databases takes practice.

Get started by setting aside some dedicated time to become familiar with the process:

• Practice by locating one reference book and one ebook in your library catalog or WorldCat
• Practice searching in freely available databases such as PubMed or ERIC
• Try some of the limiters to see what each does to your search results
• Once you find an article, what do you need to do to get it in full-text?
• Find out how to use interlibrary loan or document delivery.

Next, complete this exercise:

• Browse through a popular or scientific publication such as the science section of the New York Times or Scientific American . Find a short article that looks interesting and is easy to understand.
• an article that reports on a recent study published in a scholarly journal;
• the title of the journal;
• the name of the author(s); and
• an indication of when the original study appeared. Note: sometimes the source will say that the research was published in a latest issue of Science or Nature .
• Once you find some of these facts (journal title and the authors should be sufficient), you can start to search for the primary source in a library catalog or the library’s databases.
• Catalog search: find out if your school subscribes to a particular journal by searching for the journal by title.
• Electronic subscription—great! It means you can access the journal right away. Once you get to the online (or electronic) version of the journal, you are given a choice of searching within this publication. An author search should be sufficient to locate the article.
• Print subscription version—good! You can search in databases or a discovery service tool for your article by entering the journal title and the authors. Once you locate a record about the article, which will include volume and issue number, page numbers, the article title, you can go to the shelves where you will find the issue of the journal that includes your article.
• Microform version—still good! Again, after searching databases and locating the exact information about the article, you should be able to locate the appropriate microfilm reel or microfiche. Before the widespread and easy access to online versions of materials, microforms were used to save space by preserving documents on film. Libraries are equipped with microform readers—if you need help using a reader, ask the library staff. ( Bennard et al, 2014b )

Test Yourself

Get an article.

• Access PubMed or ERIC
• Do a subject search, using the thesaurus (for ERIC) or MeSH terms (for PubMed)
• Do a keyword search
• Supplement your subject search with keywords, using advanced search tools like Boolean operators, truncation, or phrase searching
• Limit your search by language, date of publication or PICO factor
• Access the full text of an article you find.
• If full text is not available, find out how to request the article through interlibrary loan

In your general topic area, do you know:

• The core source materials?
• The most significant theories?
• The major issues and debates surrounding your topic area?
• The key political, social, economic, legal, environmental, and/or technological aspects of your topic?
• The origins of your topic?
• The definitions for your topic?
• How knowledge in your topic area is organized?
• What problems or solutions have been addressed to date?
• If you don’t know the answers to these questions, do you know how to find the answers?

Image attributions

Literature Reviews for Education and Nursing Graduate Students Copyright © by Linda Frederiksen is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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• Subject guides
• Researching for your literature review
• Literature sources

Researching for your literature review: Literature sources

• Literature reviews
• Before you start
• Develop a search strategy
• Keyword search activity
• Subject search activity
• Combined keyword and subject searching
• Online tutorials
• Apply search limits
• Run a search in different databases
• Supplementary searching
• Save your searches
• Manage results

Scholarly databases

It's important to make a considered decision as to where to search for your review of the literature. It's uncommon for a disciplinary area to be covered by a single publisher, so searching a single publisher platform or database is unlikely to give you sufficient coverage of studies for a review. A good quality literature review involves searching a number of databases individually.

The most common method is to search a combination of large inter-disciplinary databases such as Scopus & Web of Science Core Collection, and some subject-specific databases (such as PsycInfo or EconLit etc.). The Library databases are an excellent place to start for sources of peer-reviewed journal articles.

Depending on disciplinary expectations, or the topic of our review, you may also need to consider sources or search methods other than database searching. There is general information below on searching grey literature. However, due to the wide varieties of grey literature available, you may need to spend some time investigating sources relevant for your specific need.

Grey literature

Grey literature is information which has been published informally or non-commercially (where the main purpose of the producing body is not commercial publishing) or remains unpublished. One example may be Government publications.

Grey literature may be included in a literature review to minimise publication bias . The quality of grey literature can vary greatly - some may be peer reviewed whereas some may not have been through a traditional editorial process.

See the Grey Literature guide for further information on finding and evaluating grey sources.

See the Moodle book MNHS: Systematically searching the grey literature for a comprehensive module on grey literature for systematic reviews.

In certain disciplines (such as physics) there can be a culture of preprints being made available prior to submissions to journals. There has also been a noticeable rise in preprints in medical and health areas in the wake of Covid-19.

If preprints are relevant for you, you can search preprint servers directly. A workaround might be to utilise a search engine such as Google Scholar to search specifically for preprints, as Google Scholar has timely coverage of most preprint servers including ArXiv, RePec, SSRN, BioRxiv, and MedRxiv.

Articles in Press are not preprints, but are accepted manuscripts that are not yet formally published. Articles in Press have been made available as an early access online version of a paper that may not yet have received its final formatting or an allocation of a volume/issue number. As well as being available on a journal's website, Articles in Press are available in databases such as Scopus and Web of Science, and so (unlike preprints) don't necessarily require a separate search.

Conference papers

Conference papers are typically published in conference proceedings (the collection of papers presented at a conference), and may be found on an organisation or Society's website, as a journal, or as a special issue of journal.

In certain disciplines (such as computer science), conference papers may be highly regarded as a form of scholarly communication; the conferences are highly selective, the papers are generally peer reviewed, and papers are published in proceedings affiliated with high-quality publishing houses.

Conference papers may be indexed in a range of scholarly databases. If you only want to see conference papers, database limits can be used to filter results, or try a specific index such as the examples below:

• Conference proceedings citation index. Social science & humanities (CPCI-SSH)
• Conference proceedings citation index. Science (CPCI-S)
• ASME digital library conference proceedings

Honours students and postgraduates may request conference papers through Interlibrary Loans . However, conference paper requests may take longer than traditional article requests as they can be difficult to locate; they may have been only supplied to attendees or not formally published. Sometimes only the abstract is available.

If you are specifically looking for statistical data, try searching for the keyword statistics in a Google Advanced Search and limiting by a relevant site or domain. Below are some examples of sites, or you can try a domain such as .gov for government websites.

Statistical data can be found in the following selected sources:

• Australian Bureau of Statistics
• World Health Organization: Health Data and statistics
• Higher Education Statistics
• UNESCO Institute for Statistics
• Tourism Australia Statistics

For a list of databases that include statistics see: Databases by Subject: Statistics .

If you are specifically looking for information found in newspapers, the library has a large collection of Australian and overseas newspapers, both current and historical.

To search the full-text of newspapers in electronic format use a database such as  Newsbank.

Alternatively, see the Newspapers subject guide for comprehensive information on newspaper sources available via Monash University library and open source databases, as well as searching tips, online videos and more.

Dissertations and theses

The Monash University Library Theses subject guide provides resources and guidelines for locating and accessing theses (dissertations) produced by Monash University as well as other universities in Australia and internationally.  

International theses:

There are a number of theses databases and repositories.

A popular source is:

• ProQuest Dissertations & Theses Global  which predominantly, covers North American masters and doctoral theses. Full text is available for theses added since 1997. 

Australia and New Zealand theses:

Theses that are available in the library can be found using the  Search catalogue.

These include:

• Monash doctoral, masters and a small number of honours theses 
• other Australian and overseas theses that have been purchased for the collection.

Formats include print (not available for loan), microfiche and online (some may have access restrictions).

Trove includes doctoral, masters and some honours theses from all Australian and New Zealand universities, as well as theses awarded elsewhere but held by Australian institutions.

Tips:  

• Type in the title, author surname and/or keywords. Then on the results page refine your search to 'thesis'.
• Alternatively, use the Advanced search and include 'thesis' as a keyword or limi t your result to format = thesis
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Literature Review - what is a Literature Review, why it is important and how it is done

The research process.

• Evaluating Literature Reviews and Sources
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• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings
• Useful Resources

Finding sources (scholarly articles, research books, dissertations) for your literature review is part of the research process, a process that is iterative--you go back and forth along the process as new information is gather and analyze until all necessary data is acquire and you are ready to write. The main steps in this research process are:

Searching : While searching take note of what other keywords are used to describe your topic  and use them to do more searches

– Most articles include a keyword section – Key concepts may change name through time so make sure to check for variations

Organising : Start organizing your results by categories/key concepts or any organizing principle that make sense for you. This will help you later when you are ready to analyze your findings

Analysing : While reading, start making notes of key concepts and commonalities and disagreement among the research articles you find.

– Create a spreadsheet document to record what articles you are finding useful and why. – Create fields to write summaries of articles or quotes for future citing and paraphrasing .

Writing : Synthesize your findings. Use your own voice to explain to your readers what you learn about the literature your search; its weaknesses and strengths; what is missing or ignore

Repeat : at any given time of the process you can go back to a previous step as necessary

There is no magic number regarding how many sources you are going to need for your literature review, it all depends on the topic and what type of the literature review you are doing:

► Are you working on an emerging topic? You are not likely to find many sources, which is good because you are trying to prove that this is a topic that needs more research. But, it is not enough to say that you found few or no articles on your topic in your field. You need to look broadly to other disciplines (also known as triangulation ) to see if your research topic has been studied from other perspectives as a way to validate the uniqueness of your research question.

► Are you working on  something that has been studied extensively? Then you are going to find many sources and you will want to limit how far you want to look back. Use limiters to eliminate research that may be dated and opt to search for resources published within the last 5-10 years.

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What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

APA7 Style resources

APA Style Blog - for those harder to find answers

1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
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• Literature Review: The What, Why and How-to Guide
• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

• UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
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Literature Review: Lit Review Sources

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Where do I find information for a literature review?

Research is done by...

...by way of...

...communicated through...

...and organized in...

Types of sources for a review...

• Primary source: Usually a report by the original researchers of a study (unfiltered sources)
• Secondary source: Description or summary by somebody other than the original researcher, e.g. a review article (filtered sources)
• Conceptual/theoretical: Papers concerned with description or analysis of theories or concepts associated with the topic
• Anecdotal/opinion/clinical: Views or opinions about the subject that are not research, review or theoretical (case studies or reports from clinical settings)

A Heirarchy of research information:

Source: SUNY Downstate Medical Center. Medical Research Library of Brooklyn. Evidence Based Medicine Course. A Guide to Research Methods: The Evidence Pyramid: http://library.downstate.edu/EBM2/2100.htm

Life Cycle of Publication

Click image to enlarge

Scientific information has a ‘life cycle’ of its own… it is born as an idea, and then matures and becomes more available to the public. First it appears within the so-called ‘invisible college’ of experts in the field, discussed at conferences and symposia or posted as pre-prints for comments and corrections. Then it appears in the published literature (the primary literature), often as a journal article in a peer-reviewed journal.

Researchers can use the indexing and alerting services of the secondary literature to find out what has been published in a field. Depending on how much information is added by the indexer or abstracter, this may take a few months (though electronic publication has sped up this process). Finally, the information may appear in more popular or reference sources, sometimes called the tertiary literature.

The person beginning a literature search may take this process in reverse: using tertiary sources for general background, then going to the secondary literature to survey what has been published, following up by finding the original (primary) sources, and generating their own research Idea.

(Original content by Wade Lee-Smith)

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Literature Review: The What, Why and How-to Guide: Literature Reviews?

• Literature Reviews?
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What is a Literature Review?

So, what is a literature review .

"A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available or a set of summaries." - Quote from Taylor, D. (n.d)."The Literature Review: A Few Tips on Conducting it".

• Citation: "The Literature Review: A Few Tips on Conducting it"

What kinds of literature reviews are written?

Each field has a particular way to do reviews for academic research literature. In the social sciences and humanities the most common are:

• Narrative Reviews: The purpose of this type of review is to describe the current state of the research on a specific research topic and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weaknesses, and gaps are identified. The review ends with a conclusion section that summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.
• Book review essays/ Historiographical review essays : A type of literature review typical in History and related fields, e.g., Latin American studies. For example, the Latin American Research Review explains that the purpose of this type of review is to “(1) to familiarize readers with the subject, approach, arguments, and conclusions found in a group of books whose common focus is a historical period; a country or region within Latin America; or a practice, development, or issue of interest to specialists and others; (2) to locate these books within current scholarship, critical methodologies, and approaches; and (3) to probe the relation of these new books to previous work on the subject, especially canonical texts. Unlike individual book reviews, the cluster reviews found in LARR seek to address the state of the field or discipline and not solely the works at issue.” - LARR

What are the Goals of Creating a Literature Review?

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 
• Baumeister, R.F. & Leary, M.R. (1997). "Writing narrative literature reviews," Review of General Psychology , 1(3), 311-320.

When do you need to write a Literature Review?

• When writing a prospectus or a thesis/dissertation
• When writing a research paper
• When writing a grant proposal

In all these cases you need to dedicate a chapter in these works to showcase what has been written about your research topic and to point out how your own research will shed new light into a body of scholarship.

Where I can find examples of Literature Reviews?

Note:  In the humanities, even if they don't use the term "literature review", they may have a dedicated  chapter that reviewed the "critical bibliography" or they incorporated that review in the introduction or first chapter of the dissertation, book, or article.

• UCSB electronic theses and dissertations In partnership with the Graduate Division, the UC Santa Barbara Library is making available theses and dissertations produced by UCSB students. Currently included in ADRL are theses and dissertations that were originally filed electronically, starting in 2011. In future phases of ADRL, all theses and dissertations created by UCSB students may be digitized and made available.

Where to Find Standalone Literature Reviews

Literature reviews are also written as standalone articles as a way to survey a particular research topic in-depth. This type of literature review looks at a topic from a historical perspective to see how the understanding of the topic has changed over time. 

• Find e-Journals for Standalone Literature Reviews The best way to get familiar with and to learn how to write literature reviews is by reading them. You can use our Journal Search option to find journals that specialize in publishing literature reviews from major disciplines like anthropology, sociology, etc. Usually these titles are called, "Annual Review of [discipline name] OR [Discipline name] Review. This option works best if you know the title of the publication you are looking for. Below are some examples of these journals! more... less... Journal Search can be found by hovering over the link for Research on the library website.

Social Sciences

• Annual Review of Anthropology
• Annual Review of Political Science
• Annual Review of Sociology
• Ethnic Studies Review

Hard science and health sciences:

• Annual Review of Biomedical Data Science
• Annual Review of Materials Science
• Systematic Review From journal site: "The journal Systematic Reviews encompasses all aspects of the design, conduct, and reporting of systematic reviews" in the health sciences.
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Ten Simple Rules for Writing a Literature Review

Marco pautasso.

1 Centre for Functional and Evolutionary Ecology (CEFE), CNRS, Montpellier, France

2 Centre for Biodiversity Synthesis and Analysis (CESAB), FRB, Aix-en-Provence, France

Literature reviews are in great demand in most scientific fields. Their need stems from the ever-increasing output of scientific publications [1] . For example, compared to 1991, in 2008 three, eight, and forty times more papers were indexed in Web of Science on malaria, obesity, and biodiversity, respectively [2] . Given such mountains of papers, scientists cannot be expected to examine in detail every single new paper relevant to their interests [3] . Thus, it is both advantageous and necessary to rely on regular summaries of the recent literature. Although recognition for scientists mainly comes from primary research, timely literature reviews can lead to new synthetic insights and are often widely read [4] . For such summaries to be useful, however, they need to be compiled in a professional way [5] .

When starting from scratch, reviewing the literature can require a titanic amount of work. That is why researchers who have spent their career working on a certain research issue are in a perfect position to review that literature. Some graduate schools are now offering courses in reviewing the literature, given that most research students start their project by producing an overview of what has already been done on their research issue [6] . However, it is likely that most scientists have not thought in detail about how to approach and carry out a literature review.

Reviewing the literature requires the ability to juggle multiple tasks, from finding and evaluating relevant material to synthesising information from various sources, from critical thinking to paraphrasing, evaluating, and citation skills [7] . In this contribution, I share ten simple rules I learned working on about 25 literature reviews as a PhD and postdoctoral student. Ideas and insights also come from discussions with coauthors and colleagues, as well as feedback from reviewers and editors.

Rule 1: Define a Topic and Audience

How to choose which topic to review? There are so many issues in contemporary science that you could spend a lifetime of attending conferences and reading the literature just pondering what to review. On the one hand, if you take several years to choose, several other people may have had the same idea in the meantime. On the other hand, only a well-considered topic is likely to lead to a brilliant literature review [8] . The topic must at least be:

• interesting to you (ideally, you should have come across a series of recent papers related to your line of work that call for a critical summary),
• an important aspect of the field (so that many readers will be interested in the review and there will be enough material to write it), and
• a well-defined issue (otherwise you could potentially include thousands of publications, which would make the review unhelpful).

Ideas for potential reviews may come from papers providing lists of key research questions to be answered [9] , but also from serendipitous moments during desultory reading and discussions. In addition to choosing your topic, you should also select a target audience. In many cases, the topic (e.g., web services in computational biology) will automatically define an audience (e.g., computational biologists), but that same topic may also be of interest to neighbouring fields (e.g., computer science, biology, etc.).

Rule 2: Search and Re-search the Literature

After having chosen your topic and audience, start by checking the literature and downloading relevant papers. Five pieces of advice here:

• keep track of the search items you use (so that your search can be replicated [10] ),
• keep a list of papers whose pdfs you cannot access immediately (so as to retrieve them later with alternative strategies),
• use a paper management system (e.g., Mendeley, Papers, Qiqqa, Sente),
• define early in the process some criteria for exclusion of irrelevant papers (these criteria can then be described in the review to help define its scope), and
• do not just look for research papers in the area you wish to review, but also seek previous reviews.

The chances are high that someone will already have published a literature review ( Figure 1 ), if not exactly on the issue you are planning to tackle, at least on a related topic. If there are already a few or several reviews of the literature on your issue, my advice is not to give up, but to carry on with your own literature review,

The bottom-right situation (many literature reviews but few research papers) is not just a theoretical situation; it applies, for example, to the study of the impacts of climate change on plant diseases, where there appear to be more literature reviews than research studies [33] .

• discussing in your review the approaches, limitations, and conclusions of past reviews,
• trying to find a new angle that has not been covered adequately in the previous reviews, and
• incorporating new material that has inevitably accumulated since their appearance.

When searching the literature for pertinent papers and reviews, the usual rules apply:

• be thorough,
• use different keywords and database sources (e.g., DBLP, Google Scholar, ISI Proceedings, JSTOR Search, Medline, Scopus, Web of Science), and
• look at who has cited past relevant papers and book chapters.

Rule 3: Take Notes While Reading

If you read the papers first, and only afterwards start writing the review, you will need a very good memory to remember who wrote what, and what your impressions and associations were while reading each single paper. My advice is, while reading, to start writing down interesting pieces of information, insights about how to organize the review, and thoughts on what to write. This way, by the time you have read the literature you selected, you will already have a rough draft of the review.

Of course, this draft will still need much rewriting, restructuring, and rethinking to obtain a text with a coherent argument [11] , but you will have avoided the danger posed by staring at a blank document. Be careful when taking notes to use quotation marks if you are provisionally copying verbatim from the literature. It is advisable then to reformulate such quotes with your own words in the final draft. It is important to be careful in noting the references already at this stage, so as to avoid misattributions. Using referencing software from the very beginning of your endeavour will save you time.

Rule 4: Choose the Type of Review You Wish to Write

After having taken notes while reading the literature, you will have a rough idea of the amount of material available for the review. This is probably a good time to decide whether to go for a mini- or a full review. Some journals are now favouring the publication of rather short reviews focusing on the last few years, with a limit on the number of words and citations. A mini-review is not necessarily a minor review: it may well attract more attention from busy readers, although it will inevitably simplify some issues and leave out some relevant material due to space limitations. A full review will have the advantage of more freedom to cover in detail the complexities of a particular scientific development, but may then be left in the pile of the very important papers “to be read” by readers with little time to spare for major monographs.

There is probably a continuum between mini- and full reviews. The same point applies to the dichotomy of descriptive vs. integrative reviews. While descriptive reviews focus on the methodology, findings, and interpretation of each reviewed study, integrative reviews attempt to find common ideas and concepts from the reviewed material [12] . A similar distinction exists between narrative and systematic reviews: while narrative reviews are qualitative, systematic reviews attempt to test a hypothesis based on the published evidence, which is gathered using a predefined protocol to reduce bias [13] , [14] . When systematic reviews analyse quantitative results in a quantitative way, they become meta-analyses. The choice between different review types will have to be made on a case-by-case basis, depending not just on the nature of the material found and the preferences of the target journal(s), but also on the time available to write the review and the number of coauthors [15] .

Rule 5: Keep the Review Focused, but Make It of Broad Interest

Whether your plan is to write a mini- or a full review, it is good advice to keep it focused 16 , 17 . Including material just for the sake of it can easily lead to reviews that are trying to do too many things at once. The need to keep a review focused can be problematic for interdisciplinary reviews, where the aim is to bridge the gap between fields [18] . If you are writing a review on, for example, how epidemiological approaches are used in modelling the spread of ideas, you may be inclined to include material from both parent fields, epidemiology and the study of cultural diffusion. This may be necessary to some extent, but in this case a focused review would only deal in detail with those studies at the interface between epidemiology and the spread of ideas.

While focus is an important feature of a successful review, this requirement has to be balanced with the need to make the review relevant to a broad audience. This square may be circled by discussing the wider implications of the reviewed topic for other disciplines.

Rule 6: Be Critical and Consistent

Reviewing the literature is not stamp collecting. A good review does not just summarize the literature, but discusses it critically, identifies methodological problems, and points out research gaps [19] . After having read a review of the literature, a reader should have a rough idea of:

• the major achievements in the reviewed field,
• the main areas of debate, and
• the outstanding research questions.

It is challenging to achieve a successful review on all these fronts. A solution can be to involve a set of complementary coauthors: some people are excellent at mapping what has been achieved, some others are very good at identifying dark clouds on the horizon, and some have instead a knack at predicting where solutions are going to come from. If your journal club has exactly this sort of team, then you should definitely write a review of the literature! In addition to critical thinking, a literature review needs consistency, for example in the choice of passive vs. active voice and present vs. past tense.

Rule 7: Find a Logical Structure

Like a well-baked cake, a good review has a number of telling features: it is worth the reader's time, timely, systematic, well written, focused, and critical. It also needs a good structure. With reviews, the usual subdivision of research papers into introduction, methods, results, and discussion does not work or is rarely used. However, a general introduction of the context and, toward the end, a recapitulation of the main points covered and take-home messages make sense also in the case of reviews. For systematic reviews, there is a trend towards including information about how the literature was searched (database, keywords, time limits) [20] .

How can you organize the flow of the main body of the review so that the reader will be drawn into and guided through it? It is generally helpful to draw a conceptual scheme of the review, e.g., with mind-mapping techniques. Such diagrams can help recognize a logical way to order and link the various sections of a review [21] . This is the case not just at the writing stage, but also for readers if the diagram is included in the review as a figure. A careful selection of diagrams and figures relevant to the reviewed topic can be very helpful to structure the text too [22] .

Rule 8: Make Use of Feedback

Reviews of the literature are normally peer-reviewed in the same way as research papers, and rightly so [23] . As a rule, incorporating feedback from reviewers greatly helps improve a review draft. Having read the review with a fresh mind, reviewers may spot inaccuracies, inconsistencies, and ambiguities that had not been noticed by the writers due to rereading the typescript too many times. It is however advisable to reread the draft one more time before submission, as a last-minute correction of typos, leaps, and muddled sentences may enable the reviewers to focus on providing advice on the content rather than the form.

Feedback is vital to writing a good review, and should be sought from a variety of colleagues, so as to obtain a diversity of views on the draft. This may lead in some cases to conflicting views on the merits of the paper, and on how to improve it, but such a situation is better than the absence of feedback. A diversity of feedback perspectives on a literature review can help identify where the consensus view stands in the landscape of the current scientific understanding of an issue [24] .

Rule 9: Include Your Own Relevant Research, but Be Objective

In many cases, reviewers of the literature will have published studies relevant to the review they are writing. This could create a conflict of interest: how can reviewers report objectively on their own work [25] ? Some scientists may be overly enthusiastic about what they have published, and thus risk giving too much importance to their own findings in the review. However, bias could also occur in the other direction: some scientists may be unduly dismissive of their own achievements, so that they will tend to downplay their contribution (if any) to a field when reviewing it.

In general, a review of the literature should neither be a public relations brochure nor an exercise in competitive self-denial. If a reviewer is up to the job of producing a well-organized and methodical review, which flows well and provides a service to the readership, then it should be possible to be objective in reviewing one's own relevant findings. In reviews written by multiple authors, this may be achieved by assigning the review of the results of a coauthor to different coauthors.

Rule 10: Be Up-to-Date, but Do Not Forget Older Studies

Given the progressive acceleration in the publication of scientific papers, today's reviews of the literature need awareness not just of the overall direction and achievements of a field of inquiry, but also of the latest studies, so as not to become out-of-date before they have been published. Ideally, a literature review should not identify as a major research gap an issue that has just been addressed in a series of papers in press (the same applies, of course, to older, overlooked studies (“sleeping beauties” [26] )). This implies that literature reviewers would do well to keep an eye on electronic lists of papers in press, given that it can take months before these appear in scientific databases. Some reviews declare that they have scanned the literature up to a certain point in time, but given that peer review can be a rather lengthy process, a full search for newly appeared literature at the revision stage may be worthwhile. Assessing the contribution of papers that have just appeared is particularly challenging, because there is little perspective with which to gauge their significance and impact on further research and society.

Inevitably, new papers on the reviewed topic (including independently written literature reviews) will appear from all quarters after the review has been published, so that there may soon be the need for an updated review. But this is the nature of science [27] – [32] . I wish everybody good luck with writing a review of the literature.

Acknowledgments

Many thanks to M. Barbosa, K. Dehnen-Schmutz, T. Döring, D. Fontaneto, M. Garbelotto, O. Holdenrieder, M. Jeger, D. Lonsdale, A. MacLeod, P. Mills, M. Moslonka-Lefebvre, G. Stancanelli, P. Weisberg, and X. Xu for insights and discussions, and to P. Bourne, T. Matoni, and D. Smith for helpful comments on a previous draft.

Funding Statement

This work was funded by the French Foundation for Research on Biodiversity (FRB) through its Centre for Synthesis and Analysis of Biodiversity data (CESAB), as part of the NETSEED research project. The funders had no role in the preparation of the manuscript.

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Literature Review

Where to search when doing a literature review.

• Find examples of literature reviews
• How to write a literature review
• How to search effectively
• Grey literature

Aim to be as comprehensive as possible when conducting a literature review. Knowing exactly where to search for information is important.

Work through the steps to find out the best databases to search for information on your research topic.

1. Start with research databases

Scopus and Web of Science are good databases to start with for any research topic and literature review.

• Scopus Scopus is a large multidisciplinary database covering published material in the humanities and sciences. It also provides citation analysis of authors and subject areas. Searching Scopus tutorial - Includes access to Scival via expanded top menu (Elsevier personal registration required).
• Web of Science - Core Collection The leading citation index' of scholarly literature, chemical reactions and author information. Includes citation databases: Sciences Expanded (1965+), Social Sciences (1965+), Arts & Humanities (1975+). Conference Proceedings (1990+), Emerging Sources Citation (2005+) , Current Chemical Reactions (1985+) and Index Chemicus (1993+) Access InCites benchmarking & analytics tools via the menu bar at the top of the screen.

2. Focus your search with specific databases

Select two or three discipline/specialist databases to conduct your search for comprehensive results.

Our subject guides will help you find databases relevant to major subject areas in each discipline and specific materials relevant to your research.

• Discipline subject guides
• News sources

3. Find books, theses and more

If you're looking for a specific medium (book, thesis, journal, etc.) for your research, try the following:

• Finding Theses Help finding theses at UOW, Australia and around the world and how to access them
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Conduct a literature review

What is a literature review.

A literature review is a summary of the published work in a field of study. This can be a section of a larger paper or article, or can be the focus of an entire paper. Literature reviews show that you have examined the breadth of knowledge and can justify your thesis or research questions. They are also valuable tools for other researchers who need to find a summary of that field of knowledge.

Unlike an annotated bibliography, which is a list of sources with short descriptions, a literature review synthesizes sources into a summary that has a thesis or statement of purpose—stated or implied—at its core.

How do I write a literature review?

Step 1: define your research scope.

• What is the specific research question that your literature review helps to define?
• Are there a maximum or minimum number of sources that your review should include?

Ask us if you have questions about refining your topic, search methods, writing tips, or citation management.

Step 2: Identify the literature

Start by searching broadly. Literature for your review will typically be acquired through scholarly books, journal articles, and/or dissertations. Develop an understanding of what is out there, what terms are accurate and helpful, etc., and keep track of all of it with citation management tools . If you need help figuring out key terms and where to search, ask us .

Use citation searching to track how scholars interact with, and build upon, previous research:

• Mine the references cited section of each relevant source for additional key sources
• Use Google Scholar or Scopus to find other sources that have cited a particular work

Step 3: Critically analyze the literature

Key to your literature review is a critical analysis of the literature collected around your topic. The analysis will explore relationships, major themes, and any critical gaps in the research expressed in the work. Read and summarize each source with an eye toward analyzing authority, currency, coverage, methodology, and relationship to other works. The University of Toronto's Writing Center provides a comprehensive list of questions you can use to analyze your sources.

Step 4: Categorize your resources

Divide the available resources that pertain to your research into categories reflecting their roles in addressing your research question. Possible ways to categorize resources include organization by:

• methodology
• theoretical/philosophical approach

Regardless of the division, each category should be accompanied by thorough discussions and explanations of strengths and weaknesses, value to the overall survey, and comparisons with similar sources. You may have enough resources when:

• You've used multiple databases and other resources (web portals, repositories, etc.) to get a variety of perspectives on the research topic.
• The same citations are showing up in a variety of databases.

Additional resources

Undergraduate student resources.

• Literature Review Handout (University of North Carolina at Chapel Hill)
• Learn how to write a review of literature (University of Wisconsin-Madison)

Graduate student and faculty resources

• Information Research Strategies (University of Arizona)
• Literature Reviews: An Overview for Graduate Students (NC State University)
• Oliver, P. (2012). Succeeding with Your Literature Review: A Handbook for Students [ebook]
• Machi, L. A. & McEvoy, B. T. (2016). The Literature Review: Six Steps to Success [ebook]
• Graustein, J. S. (2012). How to Write an Exceptional Thesis or Dissertation: A Step-by-Step Guide from Proposal to Successful Defense [ebook]
• Thomas, R. M. & Brubaker, D. L. (2008). Theses and Dissertations: A Guide to Planning, Research, and Writing

Conducting a Literature Review

• Getting Started
• Define your Research Question
• Finding Sources
• Evaluating Sources
• Organizing the Review
• Cite and Manage your Sources

Additional Resources

• Using Wikipedia by the University of Pittsburgh Library System

Finding Sources for a Literature Review: Introduction

There are multiple ways to find sources for your literature review, or any type of research project. Depending on your level of experience with the topic, the types of sources required by your assignment or research, or the resources you have available at the time, you may want to pursue one or more of the below methods of searching. (Tip: When in doubt, ask your professor what they recommend!)

Not all sources are created equal, and not all methods of searching are right for every purpose! Take care to think carefully about where you are in the research process, and determine which of these would be the best suited for your needs. If you need help with this step, professors, tutors, and librarians at ACPHS are always happy to help. 

Basic Information Gathering & Keyword Mining: Course notes, textbooks, Wikipedia

With a large research project, particularly one you don't have a great deal of foundational knowledge about, sometimes it can be daunting to even figure out where to start.

A good place to begin is with your course materials; if there is a specific class associated with the assignment, then you might have some useful information already available in course notes and textbooks associated with the class. Your textbook(s) might have a chapter or even more on the topic you're studying, and notes from your teacher might be a good place to find useful keywords and background information.

It's important to note that while you might be able to use these resources in many research assignments, they are not good sources for a literature review, because they do not reflect significant scholarly research in the area of study. The benefit to using these resources is gaining background information that can help you broaden or narrow your topic and/or find useful keywords that will assist you in hunting down the appropriate literature for your review. These can help you in the pre-research stage, the preliminary information gathering that will allow you to find the sources you can actually use more effectively. 

For this task, in addition to your class materials, you have another unlikely ally: the crowdsourced online encyclopedia, Wikipedia . 

Isn't Wikipedia a bad resource? (click to expand) 

In many ways, this is correct: Wikipedia can be edited by anyone at any time, and while information added to a Wikipedia article will usually be cited and mistakes are often removed quite promptly, the fact that this website can have hundreds of anonymous contributors means that it is not appropriate for use in an academic context such as a research assignment. Wikipedia articles can be vandalized as a joke or heavily biased based on who wrote the information, so it is always important when reading an article on Wikipedia that you remain skeptical, double-check the sources cited, and remain aware that you are not looking at information high enough for use in a scholarly or academic report.

For an illustration of the ways Wikipedia is not a great place to find high-quality academic information, take a look at the article "15 Biggest Wikipedia Blunders," a collection of mistakes, hoaxes, or even libel that have caused significant confusion. These blunders were possible because of Wikipedia's anonymous editing process. As you can see from one of Wikipedia's own articles on the subject , some hoaxes or mistakes can persist for years before being discovered.

What should we use Wikipedia for? (click to expand)

Despite its weaknesses, Wikipedia can be an excellent source for non-academic research, such as answering your own personal questions and curiosities; just because it does not meet the standard required for professional or academic research doesn't mean it's insufficient for casual or personal research. (In fact, some evidence suggests it reaches a similar level of accuracy as the Encyclopedia Britannica . The primary reason it cannot be used in your research is not so much because of fear of inaccuracies -- though that is a risk -- as it's impossible to verify the author(s) and their credentials.)

In addition to your own casual research, there are three major ways Wikipedia can be useful in the preliminary research process:

1. References

Because Wikipedia requires its authors to cite their claims, at the bottom of each article is a list of the sources used. If you need to know which books, articles, or other types of literature are the most important or commonly-cited in the field, Wikipedia's list of References is a good place to begin.

For example, looking at the reference list for the Estrildidae :

Of these seven sources, the articles by Frank Gill, C. H. Oliveros, and Urban Olsson (numbers 4-6) show particular promise due to their recent publication and their association with professional organizations and/or scholarly journals. Clicking on each of these, they are all free to access the entirety of, which is fortunate; if they were not open-access, however, it would still be worth saving these citations to check on in the ACPHS library, to see if you could access them through the college.

2. Background Information

While the information you discover on Wikipedia would not be sufficient for an academic assignment, it can be perfectly useful for getting a broad overview of the topic, seeing what the most common subtopics or recent developments are, and familiarizing yourself with key terms, major players, and general information.

When you first select a topic, it can often be helpful to skim through the Wikipedia page in order to develop a foundational knowledge of the topic, which you can use to direct your search for more reliable or relevant literature.

3. Keywords & Search Terms

Similarly to #2, this method of using Wikipedia collects a handful of important words, names, or even dates that you can use to narrow down your research or literature search. Returning to the Wikipedia page for  Estrildidae :

As you can see, the yellow highlighted terms are just a few potentially valuable keywords for learning more about these birds. If I were to go to the ACPHS library website and search the Discovery platform, in addition to searching for estrildidae on its own, if I wanted to know more about the discovery of these birds I could search for "Charles Lucien Bonaparte"; if I wanted to know more about specifically the locations of these birds I could search "estrildidae AND Australia OR New Guinea," for example; if I wanted to know about the specific species, family, class, or other scientific classification, I could use the other highlighted terms to do so.

When it comes to looking for keyword, the blue text often points to related terms that might be valuable in searching, while the headings in the Table of Contents can suggest subtopics that could help narrow down your research.

So remember, while Wikipedia cannot serve as a source in and of itself because it does not meet academic standards, it can be an excellent place to begin the research process, by providing potential sources and information you can use to develop your research question and find literature that will be most relevant to your needs.

Find Books & Articles on Your Topic

• Use Discovery
• Article Databases
• Interlibrary Loan

Enter a search term here

Many different databases contain articles, reports and other documents concerned with racism in health and healthcare. Depending on the focus and context of your interest, check out these useful library databases below.

• PubMed PubMed provides access to MEDLINE®, the database of indexed citations and abstracts to medical, nursing, dental, veterinary, health care, and preclinical sciences journal articles.
• ProQuest Social Science Database Disciplines covered include anthropology, communication, criminology, economics, education, political science, psychology, social work, and sociology.
• ProQuest Nursing & Allied Health Database Covers the fields of nursing and allied health, physical and occupational therapy, cytology, histology, physiology, anatomy, gerontology, and more.
• ProQuest Research Library Covers a broad range of subjects including arts, business, education, general interest, health, humanities, international, law, military, multicultural, psychology, sciences, social sciences, and women's interests.
• Gale Academic OneFile Peer-reviewed, full-text articles from the world's leading journals and reference sources. Extensive coverage of the sciences, technology, medicine, the arts, theology, literature and other subjects

The purpose of interlibrary loan (ILL) is to provide the ACPHS community with needed material that is unavailable in our library.  To take advantage of this service you will need to register for an ILLiad account.   ILLiad is an online system that allows you to initiate and track your requests to borrow books and receive articles from other libraries.

How do I register for an ILLiad account? Visit the  Libraries' Homepage . Click the Services tab, choose Interlibrary Loan, and click on Log in to ILLiad. Use your ACPHS network username and password (the one used for Canvas) to logon and start placing requests.

Searching the Web

The ACPHS library should always be your first stop in the research process, and likely will be your last; it contains the greatest number of accessible, scholarly resources that you'll likely find. However, this doesn't mean that Google cannot be used to find valuable sources.

In general, web browsers like Google, Bing, and Yahoo pull results by  popularity  as opposed to relevance or accuracy. This means that the first results you see on one of these searches will include the sites most people have clicked on, regardless of the quality of the site's information. In addition, some companies pay for their web pages to show up at the top of the search results, adding an additional layer of potential bias or conflicts of interest:

Google (or any other search engine) is best used for the following types of resources:

• General background information and common knowledge
• News stories
• Firsthand accounts that reflect public opinion (such as editorials, blog posts, social media, etc.)
• Government-, corporate-, or organization-owned web pages

While these types of sources are not likely to be included in a literature review, other research projects may benefit from these categories of resources.

The most important thing to remember when using Google or another search engine is that the results will not necessarily be current, accurate, unbiased, or relevant. It will be more challenging to evaluate these sources than ones pulled from the ACPHS library, because the library selects specifically for materials useful in academic study.

When looking for sources for a literature review, there is another way to use Google in particular for appropriate resources: Google Scholar .

This search engine works similarly to Google, but exclusively weeds out non-academic resources. It is similar to using the ACPHS Discovery , in that a search using Google Scholar will also provide studies and reports that might be useful for your literature review. Here is an example of a Google Scholar results page:

As you can see, there are some filters on the left-hand side of the screen, though Google Scholar does not allow for the same level of refinement as Discovery does. You can see the articles and their sources, authors, and publication year, as well as how many scholars have cited them since publication. (This last tool can be a helpful way to find even more current research, or perhaps even a literature review you could use in your own.)

The one significant downside of Google Scholar is that you do not automatically have access to the resources found in the search results. With Discovery, every resource is either available directly through the ACPHS library or through an interlibrary loan request, but Google Scholar will pull up results regardless of whether you have free access or not. If you find an article that you like which the ACPHS library does not have access to, you can always submit an ILL request , but if it is not within our library network, we may not be able to provide it to you.

Overall, Google Scholar is an excellent collection of resources that, as with all online searching options, has both positives and negatives. Determining which type of search method to use depends on your assignment, topic, and other research needs.

• Using Google for Academic Research by the UC Merced Library

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• URL: https://libraryservices.acphs.edu/lit_review

Literature review sources

Sources for literature review can be divided into three categories as illustrated in table below. In your dissertation you will need to use all three categories of literature review sources:

Sources for literature review and examples

Generally, your literature review should integrate a wide range of sources such as:

• Books . Textbooks remain as the most important source to find models and theories related to the research area. Research the most respected authorities in your selected research area and find the latest editions of books authored by them. For example, in the area of marketing the most notable authors include Philip Kotler, Seth Godin, Malcolm Gladwell, Emanuel Rosen and others.
• Magazines . Industry-specific magazines are usually rich in scholarly articles and they can be effective source to learn about the latest trends and developments in the research area. Reading industry magazines can be the most enjoyable part of the literature review, assuming that your selected research area represents an area of your personal and professional interests, which should be the case anyways.
• Newspapers can be referred to as the main source of up-to-date news about the latest events related to the research area. However, the proportion of the use of newspapers in literature review is recommended to be less compared to alternative sources of secondary data such as books and magazines. This is due to the fact that newspaper articles mainly lack depth of analyses and discussions.
• Online articles . You can find online versions of all of the above sources. However, note that the levels of reliability of online articles can be highly compromised depending on the source due to the high levels of ease with which articles can be published online. Opinions offered in a wide range of online discussion blogs cannot be usually used in literature review. Similarly, dissertation assessors are not keen to appreciate references to a wide range of blogs, unless articles in these blogs are authored by respected authorities in the research area.

Your secondary data sources may comprise certain amount of grey literature as well. The term grey literature refers to type of literature produced by government, academics, business and industry in print and electronic formats, which is not controlled by commercial publishers. It is called ‘grey’ because the status of the information in grey literature is not certain. In other words, any publication that has not been peer reviewed for publication is grey literature.

The necessity to use grey literature arises when there is no enough peer reviewed publications are available for the subject of your study.

John Dudovskiy

Literature Review

What is a literature review, components of a literature review, creative commons license.

• 1. Find Sources
• 2. Evaluate Sources
• 3. Organize Information

• Contact your Librarian

A literature review is a summary and evaluation of significant documents and developments on a topic. Completing a literature review will ensure a good understanding of a topic.

Start by identifying key documents on a topic and compile a bibliography or list. Gather significant documents relating to your topic, including books, journal articles, newspaper articles, etc. Use journal citation reports to help identify frequently referenced articles.

Depending of the type of literature review being conducted you might need anywhere from 5-50 references. An undergraduate review could require anywhere from 5-20 titles, depending on the type of assignment, while a thesis would require more in depth knowledge of a topic, with 20-50 references or more. Ask your instructor for specific details.

Group the literature into key themes and theories and use these grouping as headings to organize your writing.

A literature review can be a stand-alone document, or it may be part of the introduction of an essay or thesis, providing an overview of key themes and context for the larger report.

The introduction presents the topic of research, address any controversies and provide background information and history of the topic.

The body can be broken down into headings related to themes, theories and trends in the literature. Each heading should summarize and evaluate the literature for its contributions, and identify any strengths, weaknesses, contradictions and gaps in the research.

The conclusion summarizes key concepts and trends found in the literature. The conclusion may indicate what contributions your research will make and/or suggest possibilities for future studies.

A literature review that is an introductory part of an essay or thesis should conclude by indicating what contributions your research will make to the field. The conclusion of a stand-alone literature review should suggest practical applications for the research and possibilities for future studies in the field. It may also be accompanied by an annotated bibliography, briefly summarizing each source.

• Finding Books
• Finding Articles
• Search Citators
• Evaluate Your Sources
• Cite Your Findings
• Article Citation Numbers
• Organize Information into Sections
• Draw Conclusions
• Types of Literature Reviews
• Introduction

This guide was created by Ontario Tech Libraries and is licensed under a Creative Commons Attribution International 4.0 License , except where otherwise noted. 

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• Last Updated: Mar 18, 2024 1:56 PM
• URL: https://guides.library.ontariotechu.ca/literaturereview

Eugene McDermott Library

Literature review.

• Collecting Resources for a Literature Review
• Organizing the Literature Review
• Writing the Literature Review
• Examples of Literature Reviews

Sources for Literature Review Items

Sources for a Literature Review will come from a variety of places, including:

•Books Use the Library Catalog  to see what items McDermott Library has on your topic or if McDermott Library has a specific source you need. The WorldCat   database allows you to search the catalogs on many, many libraries. WorldCat is a good place to find out what books exist on your topic.

•Reference Materials Reference Materials such as encyclopedias and dictionaries provide good overall views of topics and provide keyword hints for searching. Many will include lists of sources to consider for your literature review.

•Journals via Electronic Databases Journals are a major source of materials for a literature review. With the library's databases, you can search thousands of journals back a century or more.   

•Conference Papers At conferences, professionals and scholars explore the latest trends, share new ideas, and present new research. Searching Conference papers allows you to see research before it is published and get a feel for what is going on in a particular organization or within a particular group. 

Many electronic databases include conference proceedings, but with Conference Proceedings Citation Index database, you can search proceedings alone. 

•Dissertations & Theses Here is a link to databases licensed by UTD McDermott library with full-text access to Dissertations and Theses

Some of these are specific to Texas or UTD produced studies. Choose the Global option to search more broadly.

•Internet The general internet can be a valuable resource for information. However, it is largely unregulated. Be sure to critically evaluate internet sources. Look at the Evaluating Websites  LibGuide for suggestions on evaluating websites.

•Government Publications The U.S. government produces a wide variety of information sources, from consumer brochures to congressional reports to large amounts of data to longitudinal studies. For the United States, Usa.gov is a good place to start.  Official state websites can be helpful for individual state statistics and information. 

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• Last Updated: Mar 22, 2024 12:28 PM
• URL: https://libguides.utdallas.edu/literature-review

• Library Guides

The Literature Review

Primary and secondary sources, the literature review: primary and secondary sources.

• Searching the literature
• Grey literature
• Organising and analysing
• Systematic Reviews
• The Literature Review Toolbox

On this page

• Primary vs secondary sources: The differences explained 

Can something be both a primary and secondary source?

Research for your literature review can be categorised as either primary or secondary in nature. The simplest definition of primary sources is either original information (such as survey data) or a first person account of an event (such as an interview transcript). Whereas secondary sources are any publshed or unpublished works that describe, summarise, analyse, evaluate, interpret or review primary source materials. Secondary sources can incorporate primary sources to support their arguments.

Ideally, good research should use a combination of both primary and secondary sources. For example, if a researcher were to investigate the introduction of a law and the impacts it had on a community, he/she might look at the transcripts of the parliamentary debates as well as the parliamentary commentary and news reporting surrounding the laws at the time. 

Examples of primary and secondary sources

Primary vs secondary sources: The differences explained

Finding primary sources

• VU Special Collections  - The Special Collections at Victoria University Library are a valuable research resource. The Collections have strong threads of radical literature, particularly Australian Communist literature, much of which is rare or unique. Women and urban planning also feature across the Collections. There are collections that give you a picture of the people who donated them like Ray Verrills, John McLaren, Sir Zelman Cowen, and Ruth & Maurie Crow. Other collections focus on Australia's neighbours – PNG and Timor-Leste.
• POLICY - Sharing the latest in policy knowledge and evidence, this database supports enhanced learning, collaboration and contribution.
• Indigenous Australia  -  The Indigenous Australia database represents the collections of the Aboriginal and Torres Strait Islander Commission Library.
• Australian Heritage Bibliography - Aboriginal and Torres Strait Islander Subset (AHB-ATSIS)  - AHB is a bibliographic database that indexes and abstracts articles from published and unpublished material on Australia's natural and cultural environment. The AHB-ATSIS subset contains records that specifically relate to the Aboriginal and Torres Strait Islander peoples.include journal articles, unpublished reports, books, videos and conference proceedings from many different sources around Australia. Emphasis is placed on reports written or commissioned by government and non-government heritage agencies throughout the country.
• ATSIhealth  - The Aboriginal and Torres Strait Islander Health Bibliography (ATSIhealth), compiled by Neil Thomson and Natalie Weissofner at the School of Indigenous Australian Studies, Kurongkurl Katitjin, Edith Cowan University, is a bibliographic database that indexes published and unpublished material on Australian Indigenous health. Source documents include theses, unpublished articles, government reports, conference papers, abstracts, book chapters, books, discussion and working papers, and statistical documents. 
• National Archive of Australia  - The National Archives of Australia holds the memory of our nation and keeps vital Australian Government records safe. 
• National Library of Australia: Manuscripts  - Manuscripts collection that is wide ranging and provides rich evidence of the lives and activities of Australians who have shaped our society.
• National Library of Australia: Printed ephemera  - The National Library has been selectively collecting Australian printed ephemera since the early 1960s as a record of Australian life and social customs, popular culture, national events, and issues of national concern.
• National Library of Australia: Oral history and folklore - The Library’s Oral History and Folklore Collection dates back to the 1950’s and includes a rich and diverse collection of interviews and recordings with Australians from all walks of life.
• Historic Hansard - Commonwealth of Australia parliamentary debates presented in an easy-to-read format for historians and other lovers of political speech.
• The Old Bailey Online - A fully searchable edition of the largest body of texts detailing the lives of non-elite people ever published, containing 197,745 criminal trials held at London's central criminal court.

Whether or not a source can be considered both primary and  secondary, depends on the context. In some instances, material may act as a secondary source for one research area, and as a primary source for another. For example, Niccolò Machiavelli’s The Prince , published in 1513, is an important secondary source for any study of the various Renaissance princes in the Medici family; but the same book is also a primary source for the political thought that was characteristic of the sixteenth century because it reflects the attitudes of a person living in the 1500s.

Source: Craver, 1999, as cited in University of South Australia Library. (2021, Oct 6).  Can something be a primary and secondary source?.  University of South Australia Library. https://guides.library.unisa.edu.au/historycultural/sourcetypes

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• Last Updated: Mar 27, 2024 2:06 PM
• URL: https://libraryguides.vu.edu.au/the-literature-review

Writing a Literature Review

• Literature Review Home
• Background Research
• Types of Resources

Finding Articles

• Finding Books
• Search Techniques
• Annotated Bib Guide This link opens in a new window
• Citing Sources This link opens in a new window
• Need Help? Ask a Librarian This link opens in a new window

Where to Search

So where do you search to find the best resources to write your research paper.

Don't start with Google to do your research. You aren't going to find the scholarly sources that are best for your research there because scholarly research costs money and isn't freely available online for the most part. Luckily, the library pays to access a lot of scholarly research and makes it available through a variety of different search tools.

Looking for a specific database (such as Academic Search Premier)?

• Go to Databases A-Z

Looking for a specific journal (such as Nature)?

• Go to Journal Finder

Are you doing a general keyword search or looking for a specific article?

• Use Search Everything to find articles from Freel Library’s collections as well as from over 1,000 e-content collections.
• Use Google Scholar to find articles across a wide range of academic literature, drawn from information from journal publishers, university repositories, and other websites that Google has identified as scholarly.

Search Everything

Google scholar, more options.

• Boston Public Library BPL eCards are virtual library cards that allow users immediate entry to all of Boston Public Library's remotely-accessible electronic resources, including magazine databases, downloadable audio, video, eBooks, and music. Students living in Massachusetts while attending school are eligible for a card. Sign up for one here.
• Interlibrary Loan MCLA faculty, librarians, administrators, students and staff may use Interlibrary Loan to request materials not found in the MCLA Library collections.
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• Last Updated: Jan 24, 2024 10:30 AM
• URL: https://library.mcla.edu/litreview

Physical Therapy

• Critical Appraisal
• Getting Started with Research
• Reference Resources
• Evidence Summaries and Clinical Guidelines
• Health Data and Statistics
• Patient/Consumer Facing Materials
• Images and Streaming Video
• Database Tutorials and Search Guidance
• Crafting a Search
• Narrowing/Filtering the Search
• Expanding the Search
• Find Grey Literature
• Save Your Searches
• Cite and Manage Sources
• What are Literature Reviews?
• Conducting & Reporting Systematic Reviews
• Finding Systematic Reviews
• Tutorials & Tools for Literature Reviews

Types of Literature Reviews

Literature reviews are comprehensive summaries and syntheses of the previous research on a given topic.

The review purpose, methods used, and the results produced vary among different kinds of literature reviews. Some of the common types of literature review are detailed below.

Common Types of Literature Reviews 1

Narrative (literature) review.

• A broad term referring to reviews with a wide scope and non-standardized methodology
• Search strategies, comprehensiveness of literature search, time range covered and method of synthesis will vary and do not follow an established protocol

Integrative Review

• A type of literature review based on a systematic, structured literature search
• Often has a broadly defined purpose or review question
• Seeks to generate or refine and theory or hypothesis and/or develop a holistic understanding of a topic of interest
• Relies on diverse sources of data (e.g. empirical, theoretical or methodological literature; qualitative or quantitative studies)

Systematic Review

• Systematically and transparently collects and categorize existing evidence on a question of scientific, policy or management importance
• Follows a research protocol that is established  a priori
• Some sub-types of systematic reviews include: SRs of intervention effectiveness, diagnosis, prognosis, etiology, qualitative evidence, economic evidence, and more.
• Time-intensive and often takes months to a year or more to complete 
• The most commonly referred to type of evidence synthesis; sometimes confused as a blanket term for other types of reviews

Meta-Analysis

• Statistical technique for combining the findings from disparate quantitative studies
• Uses statistical methods to objectively evaluate, synthesize, and summarize results
• Often conducted as part of a systematic review

Scoping Review

• Systematically and transparently collects and categorizes existing evidence on a broad question of scientific, policy or management importance
• Seeks to identify research gaps, identify key concepts and characteristics of the literature and/or examine how research is conducted on a topic of interest
• Useful when the complexity or heterogeneity of the body of literature does not lend itself to a precise systematic review
• Useful if authors do not have a single, precise review question
• May critically evaluate existing evidence, but does not attempt to synthesize the results in the way a systematic review would 
• May take longer than a systematic review

Rapid Review

• Applies a systematic review methodology within a time-constrained setting
• Employs methodological "shortcuts" (e.g., limiting search terms and the scope of the literature search), at the risk of introducing bias
• Useful for addressing issues requiring quick decisions, such as developing policy recommendations

Umbrella Review

• Reviews other systematic reviews on a topic
• Often defines a broader question than is typical of a traditional systematic review
• Most useful when there are competing interventions to consider

1. Adapted from:

Eldermire, E. (2021, November 15). A guide to evidence synthesis: Types of evidence synthesis. Cornell University LibGuides.  https://guides.library.cornell.edu/evidence-synthesis/types

Nolfi, D. (2021, October 6). Integrative Review: Systematic vs. Scoping vs. Integrative. Duquesne University LibGuides.  https://guides.library.duq.edu/c.php?g=1055475&p=7725920

Delaney, L. (2021, November 24). Systematic reviews: Other review types. UniSA LibGuides.  https://guides.library.unisa.edu.au/SystematicReviews/OtherReviewTypes

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• Next: Conducting & Reporting Systematic Reviews >>
• Last Updated: Jun 26, 2024 3:00 PM
• URL: https://guides.nyu.edu/pt

• Academic Writing Guides

How to Write a Literature Review? A Beginner’s Guide

Sooner or later in your academic path, you will be required to compose a literature review. So, it’s important to approach this task well-prepared and understand how to write a literature review inside out. 

Are you interested in how to write lit review projects correctly and cover the subject comprehensively, from all angles? This article will explore the concept of review of literature , dwell on how to write a literature review in line with your professor’s expectations, and share a universal literature review template for your usage. 

What Is the Purpose of a Literature Review? 

To understand what should be included in a literature review , you need to understand its purpose and value in a larger work. A well-researched and written lit review usually addresses the following objectives: 

• Inform . The fundamental purpose of any review of literature is to provide the foundation of knowledge on a specific topic or phenomenon. You explore what people have learned about it from prior studies and summarize those findings to inform your readers. 
• Give credit . Another purpose of a lit review is to identify researchers who have contributed to the advancement of research on your chosen literature review topic and have produced the most valuable findings. This way, you pay tribute to those researchers and showcase your knowledge of the most considerable influencers. 
• Identify gaps . By performing a thorough review of literature , you may not only discover what is known about your topic but also find out what it yet to be learned about it. As a result of reviewing the available evidence, you may identify gaps for addressing through your academic inquiry. 
• Identify patterns . Those who know how to write a literature review can also effectively embrace data trends and patterns in the collected dataset. As a result, they can present a more nuanced analysis of the existing knowledge in your literature review and uncover dependencies that inform people’s understanding of certain phenomena and processes.  
• Contextualize research . When you perform lit review writing, you can also create a spot for your own study within the broad field of your academic research interest. This way, you show to your readers that you can effectively navigate the landscape of your academic area. 

These purposes lay the foundation for understanding how to write a literature review that will attain all academic goals. You simply need to use this list as your checklist for structuring an impactful lit review and including all vital data in it. 

How to Write a Literature Review? 

Now, we come to the main topic of this article – how to write a good literature review for dissertation projects, research papers, and other works. Follow the steps we’ve covered below to arrive at a consistent, logical piece of lit review . 

Identify Relevant Sources 

Any literature review writing starts with academic research. You should look for sources that explore your topic from various angles and provide valuable literature review findings to expand your knowledge on the subject. It’s best to look for subject-specific books first and then go through academic databases that publish journal articles. This way, you will start with the evidence of the highest reliability level and move on to expand your literature review dataset conveniently. 

Screen Sources for Quality 

The best solution on how to write a literature review without challenges is to rely on high-quality evidence. Your task is to research extensively in reliable academic databases to find peer-reviewed academic journals and books written by experts in your field. Don’t over-rely on online sources in your literature review, like blogs or opinion pieces, because they rarely possess the needed degree of credibility for an academic review. By choosing only industry-approved sources from qualified professionals, you can build a solid foundation for your writing and impress the audience. 

Determine Data Patterns and Gaps 

How to write a literature review of value for your readers? One of the best approaches is to go beyond mere summarization of what other researchers have found on the subject and to apply critical thinking and data categorization. This way, you will manage to uncover existing patterns and trends and examine those dependencies in your literature review. A systematic, critical approach is always evaluated much higher than a simple outline of what people say on your subject. 

Draft an Outline 

Now, it’s time to compose an outline for a literature review . The outline should include the main concepts you’re planning to cover in the literature review text and should structure the narrative consistently. By means of composing an outline before the actual writing process, you give yourself a hands-on roadmap for composing a logically flowing piece. As a result of using an outline, you will write the literature review faster and will avoid the risk of going off-topic. 

Compose the Review 

With a good and detailed outline, you should have no more problems or concerns about how to write a literature review . The writing process should go quickly and smoothly when you have all your evidence at your fingertips, categorized by themes and requiring only proper summarization in the text. 

We recommend starting with a broad introduction to the topic and concepts related to it. You should give definitions and explain the topic’s features and components that require attention in the research process. After that, you may briefly outline the main sections of your review and then proceed to the exploration of each section in depth. 

At times, your professor will give you a specific structure for review writing – such as the general introduction, coverage of theories, and then coverage of empirical evidence. At times, it may be a review of the data search strategy and a report on the identified resources that follow. In any case, you should follow the tutor’s prompt closely to ensure compliance with the task. 

Make Use of This Generic Literature Review Template 

Looking for a universal, ready-to-use literature review template ? Here is an effective literature review template that everyone can apply with minor tweaks to produce a high-quality review of literature . 

LITERATURE REVIEW TEMPLATE 

Introduction 

• Introduce the topic of your literature review 
• Examine its significance for your academic area 
• Determine the scope of your literature review inquiry 
• Give a brief outline of subtopics and sections included in your literature review 

Body of the literature review

• Describe the subtopic and indicate how it relates to your literature review’s main idea
• Summarize the evidence available about it 
• Compare the available data and voice your opinion 

Conclusion 

• Summarize the main points and findings from your literature review 
• State the main contribution you have managed to achieve 
• Identify the research gaps your literature review has revealed 

Use this literature review template to pump your writing muscle and get ready for new literature review challenges. 

More Pro Tips for Writing a Literature Review 

If you’re still unsure about how to do a literature review with excellence, these pro tips may improve your understanding of this task type. 

• Mind the audience . Understanding how to do a literature review for a research paper often has little to do with how to write literature review for thesis . This difference is explained by the fact that these types of academic work are of different lengths and pursue different scholarly goals. This way, you may need to cover only some basic seminal research in the review of literature for a research paper but will need to dig deeper into theoretical and applied research with deeper analysis and more critical thinking when dealing with a thesis.
• Mind the length . How long should a literature review be ? This is a vital question that you should answer before starting the outlining and writing process. Ask your professor if you’re not sure or apply the rule of thumb, where this section usually takes from 15% to 25% of the entire paper. 
• Mind the structure . It’s important to cover all lit review aspects that your professor wants to see in the paper; otherwise, you risk getting a low grade even if your literature review is comprehensive and interesting. What should a literature review include ? In most cases, you will be required to cover some seminal research works in your literature review to show that you understand who the pioneers in the field are, and what contribution they have made to the topic’s exploration. Next, you should examine relevant theories that inform studies in your subject. At the end of the literature review, you should typically cite a variety of studies of applied nature, thus showing what empirical research is conducted in your academic field.  

With these recommendations at your disposal, you’re sure to become much more proficient in how to do a lit review . If you need more help with a literature review project, welcome to use our professional and quick literature review writing service . Our experts know everything about how to write a literature review , so they will handle your literature review task with ease within the timeframe you set for them.

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JSmol Viewer

A systematic literature review and bibliometric analysis of semantic segmentation models in land cover mapping.

1. Introduction

2. materials and methods, 2.1. research questions (rqs).

• RQ1. What are the emerging patterns in land cover mapping?
• RQ2. What are the domain studies of semantic segmentation models in land cover mapping?
• RQ3. What are the data used in semantic segmentation models for land cover mapping?
• RQ4. What are the architecture and performances of semantic segmentation methodologies used in land cover mapping?

2.2. Search Strategy

2.3. study selection criteria, 2.4. eligibility and data analysis, 2.5. data synthesis, 3. results and discussion, 3.1. rq1. what are the emerging patterns in land cover mapping.

• Annual distribution of research studies
• Leading Journals
• Geographic distribution of studies
• Leading Themes and Timelines

3.2. RQ2. What Are Domain Studies of Semantic Segmentation Models in Land Cover Mapping?

• Land Cover Studies
• Precision Agriculture
• Environment
• Coastal Areas

3.3. RQ3. What Are the Data Used in Semantic Segmentation Models for Land Cover Mapping?

• Study Locations
• Data Sources
• Benchmark datasets

3.4. RQ4. What Are the Architecture and Performances of Semantic Segmentation Methodologies Used in Land Cover Mapping?

• Encoder-Decoder based structure
• Transformer-based structure
• Hybrid-based structure
• Performance analysis of semantic segmentation model structures on ISPRS 2-D labelling Potsdam and Vaihingen datasets
• Common experimental training settings

4. Challenges, Future Insights and Directions

4.1. land cover mapping.

• Extracting boundary information
• Generating Precise Land Cover Maps

4.2. Semantic Segmentation Methodologies

• Enhancing deep learning model performance
• Analysis of RS images
• Unlabeled and Imbalance RS data

5. Conclusions

Author contributions, data availability statement, acknowledgments, conflicts of interest, abbreviations.

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Ajibola, S.; Cabral, P. A Systematic Literature Review and Bibliometric Analysis of Semantic Segmentation Models in Land Cover Mapping. Remote Sens. 2024 , 16 , 2222. https://doi.org/10.3390/rs16122222

Ajibola S, Cabral P. A Systematic Literature Review and Bibliometric Analysis of Semantic Segmentation Models in Land Cover Mapping. Remote Sensing . 2024; 16(12):2222. https://doi.org/10.3390/rs16122222

Ajibola, Segun, and Pedro Cabral. 2024. "A Systematic Literature Review and Bibliometric Analysis of Semantic Segmentation Models in Land Cover Mapping" Remote Sensing 16, no. 12: 2222. https://doi.org/10.3390/rs16122222

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Placebo effects in randomized trials of pharmacological and neurostimulation interventions for mental disorders: An umbrella review

• Nathan T. M. Huneke   ORCID: orcid.org/0000-0001-5981-6707 1 , 2 ,
• Jay Amin   ORCID: orcid.org/0000-0003-3792-0428 1 , 2 ,
• David S. Baldwin 1 , 2 , 3 ,
• Alessio Bellato 4 , 5 ,
• Valerie Brandt   ORCID: orcid.org/0000-0002-3208-2659 5 , 6 ,
• Samuel R. Chamberlain 1 , 2 ,
• Christoph U. Correll   ORCID: orcid.org/0000-0002-7254-5646 7 , 8 , 9 , 10 ,
• Luis Eudave 11 ,
• Matthew Garner 1 , 5 , 12 ,
• Corentin J. Gosling 5 , 13 , 14 ,
• Catherine M. Hill 1 , 15 ,
• Ruihua Hou 1 ,
• Oliver D. Howes   ORCID: orcid.org/0000-0002-2928-1972 16 , 17 , 18 ,
• Konstantinos Ioannidis 1 , 2 ,
• Ole Köhler-Forsberg 19 , 20 ,
• Lucia Marzulli 21 ,
• Claire Reed   ORCID: orcid.org/0000-0003-1385-4729 5 ,
• Julia M. A. Sinclair 1 ,
• Satneet Singh 2 ,
• Marco Solmi   ORCID: orcid.org/0000-0003-4877-7233 5 , 22 , 23 , 24 , 25   na1 &
• Samuele Cortese   ORCID: orcid.org/0000-0001-5877-8075 1 , 5 , 26 , 27 , 28   na1  

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• Drug discovery
• Neuroscience
• Psychiatric disorders

There is a growing literature exploring the placebo response within specific mental disorders, but no overarching quantitative synthesis of this research has analyzed evidence across mental disorders. We carried out an umbrella review of meta-analyses of randomized controlled trials (RCTs) of biological treatments (pharmacotherapy or neurostimulation) for mental disorders. We explored whether placebo effect size differs across distinct disorders, and the correlates of increased placebo effects. Based on a pre-registered protocol, we searched Medline, PsycInfo, EMBASE, and Web of Knowledge up to 23.10.2022 for systematic reviews and/or meta-analyses reporting placebo effect sizes in psychopharmacological or neurostimulation RCTs. Twenty meta-analyses, summarising 1,691 RCTs involving 261,730 patients, were included. Placebo effect size varied, and was large in alcohol use disorder ( g  = 0.90, 95% CI [0.70, 1.09]), depression ( g  = 1.10, 95% CI [1.06, 1.15]), restless legs syndrome ( g  = 1.41, 95% CI [1.25, 1.56]), and generalized anxiety disorder ( d  = 1.85, 95% CI [1.61, 2.09]). Placebo effect size was small-to-medium in obsessive-compulsive disorder ( d  = 0.32, 95% CI [0.22, 0.41]), primary insomnia ( g  = 0.35, 95% CI [0.28, 0.42]), and schizophrenia spectrum disorders (standardized mean change = 0.33, 95% CI [0.22, 0.44]). Correlates of larger placebo response in multiple mental disorders included later publication year (opposite finding for ADHD), younger age, more trial sites, larger sample size, increased baseline severity, and larger active treatment effect size. Most (18 of 20) meta-analyses were judged ‘low’ quality as per AMSTAR-2. Placebo effect sizes varied substantially across mental disorders. Future research should explore the sources of this variation. We identified important gaps in the literature, with no eligible systematic reviews/meta-analyses of placebo response in stress-related disorders, eating disorders, behavioural addictions, or bipolar mania.

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Introduction.

A placebo is an ‘inactive’ substance or ‘sham’ technique that is used as a control for assessing the efficacy of an active treatment [ 1 ]. However, study participants in a placebo control group may experience considerable symptom improvements - a ‘placebo response’ [ 1 , 2 , 3 ]. Statistical artifacts or non-specific effects account for some of the placebo response. For example, many individuals seek treatment and are enrolled in clinical trials while their symptoms are at their worst. Their symptoms will gradually return to their usual severity (‘regression to the mean’), giving the appearance of a placebo response [ 4 ]. Further, it has been suggested that the placebo response is exacerbated due to unreliable ratings as well as baseline symptom severity inflation if raters are aware of severity criteria for entry to a trial [ 5 , 6 ]. Other potential sources of apparent placebo responses include sampling biases caused by the withdrawal of the least improved patients in the placebo arm, non-specific beneficial effects resulting from interactions with staff delivering the trial, environmental effects due to inpatient care during placebo-controlled trials, or other unaccounted for factors, such as dietary or exercise changes during the trial [ 7 , 8 , 9 ]. Nonetheless, there is evidence that placebo administration results in ‘true’ - or non-artefactual - placebo effects, that is, identifiable changes in biological systems [ 1 , 10 , 11 ]. For example, placebo administration is capable of causing immunosuppression [ 12 , 13 ], placebo effects in Parkinson’s disease are driven by striatal dopamine release [ 10 , 14 ], and placebo analgesia is mediated by endogenous opioid release [ 15 , 16 ]. Furthermore, there is evidence that placebo effects in depressive and anxiety disorders are correlated with altered activity in the ventral striatum, orbitofrontal cortex, rostral anterior cingulate cortex, and the default mode network [ 17 ]. The placebo effect size can be increased through the use of verbal suggestions and conditioning procedures, thus suggesting the underlying role of psychological mechanisms including learning and expectations [ 11 , 18 ].

Across age groups, treatment modalities, and diverse mental disorders, biological treatments (pharmacotherapy or neurostimulation) do reduce symptoms [ 19 , 20 , 21 , 22 ], but only a subgroup of patients experience a clinically significant symptom response or enter remission [ 23 , 24 , 25 ]. Furthermore, current medications may also have unfavourable side effects [ 23 , 26 , 27 , 28 , 29 , 30 , 31 ]. Given the high prevalence of mental disorders and their significant socioeconomic burden [ 32 , 33 , 34 ], there is a need to develop more effective and safer psychopharmacologic and neurostimulation treatments. However, in randomized-controlled trials (RCTs), the magnitude of the placebo response may be considerable, which can affect the interpretation of their results [ 35 , 36 , 37 ]. For example, in antipsychotic trials over the past 40 years, placebo response has increased while medication response has remained consistent [ 38 , 39 ]. Consequently, the trial’s ability to statistically differentiate between an active medication and a placebo is diminished [ 40 ]. Indeed, large placebo response rates have been implicated in hindering psychotropic drug development [ 41 , 42 ]. The increased placebo response can also affect larger data synthesis approaches, such as network meta-analysis, in which assumptions about placebo responses (e.g. stability over time) might affect the validity of results [ 43 ].

Improved understanding of participant, trial, and mental disorder-related factors that contribute to placebo response might allow better clinical trial design to separate active treatment from placebo effects. There is a growing body of research, including individual studies and systematic reviews/meta-analyses, examining the placebo response within specific mental disorders [ 35 ]. However, to date, no overarching synthesis of this literature, to detect any similarities or differences across mental disorders, has been published. We therefore carried out an umbrella review of meta-analyses to address this need. We aimed to assess the placebo effect size in RCTs for a range of mental disorders, whether the effect size differs across distinct mental disorders, and identify any correlates of increased placebo effect size or response rate.

The protocol for this systematic umbrella review was pre-registered on the open science framework ( https://osf.io/fxvn4/ ) and published [ 44 ]. Deviations from this protocol, and additions to it, were: eight authors were involved in record screening rather than two; we reported effect sizes pooled across age groups and analyses comparing placebo effect sizes between age groups; and we included a meta-analysis that incorporated trials of dietary supplements as well as medications in autism. For the rationale behind these decisions, see eMethods.

Eight authors (NH, AB, VB, LE, OKF, LM, CR, SS) carried out the systematic review and data extraction independently in pairs. Discrepancies were resolved through consensus or through arbitration by a third reviewer (NH or SCo). We searched, without date or language restrictions, up to 23.10.2022, Medline, PsycInfo, EMBASE + EMBASE Classic, and Web of Knowledge for systematic reviews with or without meta-analyses of RCTs of biological treatments (psychopharmacotherapy or neurostimulation) compared with a placebo or sham treatment in individuals with mental disorders diagnosed according to standardized criteria. The full search strategy is included in eMethods. We also sought systematic reviews of RCTs conducted in patients with sleep-wake disorders, since these disorders are included in the DSM-5 and their core symptoms overlap with those of mental disorders [ 45 ]. We retained systematic reviews with or without meta-analyses that reported within-group changes in symptoms in the placebo arm.

Next, to prevent duplication of data, a matrix containing all eligible systematic reviews/meta-analyses for each category of mental disorder was created. Where there were multiple eligible systematic reviews/meta-analyses for the same disorder and treatment, we preferentially included meta-analyses, and if multiple eligible meta-analyses remained, then we included the one containing the largest number of studies for the same disorder and treatment, in line with recent umbrella reviews [ 46 , 47 ].

Data were extracted by at least two among six reviewers (AB, VB, LE, OKF, CR, SS) independently in pairs via a piloted form. All extracted data were further checked by a third reviewer (NH). See eMethods for a list of extracted data.

Our primary outcome was the pre-post effect size of the placebo/sham related to the condition-specific primary symptom change for each mental disorder. Secondary outcomes included any other reported clinical outcomes in eligible reviews. We report effect sizes calculated within-group from baseline and post-treatment means by meta-analysis authors, including Cohen’s d and Hedges’ g for repeated measures, which account for both mean difference and correlation between paired observations; and standardized mean change, where the average change score is divided by standard deviation of the change scores. We interpreted the effect size in line with the suggestion by Cohen [ 48 ], i.e. small (~0.2), medium (~0.5), or large (~0.8).

In addition, we extracted data regarding potential correlates of increased placebo effect size or response rate (as defined and assessed by the authors of each meta-analysis) in each mental disorder identified through correlation analyses or meta-regression. Where available, results from multivariate analyses were preferred.

The methodological quality of included reviews was assessed by at least two among six reviewers (AB, VB, LE, OKF, NH, CR) independently and in pairs using the AMSTAR-2 tool, a critical appraisal tool that enables reproducible assessments of the conduct of systematic reviews [ 49 ]. The methodological quality of each included review was rated as high, moderate, low, or critically low.

Our initial search identified 6,108 records. After screening titles and abstracts, we obtained and assessed 115 full-text reports (see eResults for a list of articles excluded following full-text assessment, with reasons). Of these, 20 were deemed eligible, and all were systematic reviews with meta-analysis (Fig.  1 ). In total, the 20 included meta-analyses synthesized data from 1,691 RCTs (median 55) involving 261,730 patients (median 5,365). These meta-analyses were published between 2007 and 2022 and involved individuals with the following mental disorders: major depressive disorder (MDD; n  = 6) [ 50 , 51 , 52 , 53 , 54 , 55 ], anxiety disorders ( n  = 4) [ 55 , 56 , 57 , 58 ], schizophrenia spectrum disorders ( n  = 3) [ 38 , 59 , 60 ], alcohol use disorder (AUD; n  = 1) [ 61 ], attention-deficit/hyperactivity disorder (ADHD; n  = 1) [ 62 ], autism spectrum disorders ( n  = 1) [ 63 ], bipolar depression ( n  = 1) [ 64 ], intellectual disability ( n  = 1) [ 65 ], obsessive-compulsive disorder (OCD; n  = 1) [ 66 ], primary insomnia ( n  = 1) [ 67 ], and restless legs syndrome (RLS; n  = 1) [ 68 ].

Twenty meta-analyses were included.

The methodological quality of the included meta-analyses according to AMSTAR-2 ratings was high in two meta-analyses (ADHD and autism), low in four meta-analyses, and critically low in the remaining 14 meta-analyses (Table  1 ). The most common sources of bias that led to downgrading on the AMSTAR-2 were: no list of excluded full-text articles with reasons ( k  = 14), no explicit statement that the protocol was pre-registered ( k  = 14), and no assessment of the potential impact of risk of bias in individual studies on the results ( k  = 13). The full reasoning behind our AMSTAR-2 ratings is included in eResults.

Our first objective was to determine placebo effect sizes across mental conditions. Data regarding within-group placebo efficacy were reported in sixteen of the included meta-analyses [ 38 , 50 , 52 , 53 , 55 , 56 , 57 , 58 , 60 , 61 , 62 , 63 , 65 , 66 , 67 , 68 ]. Placebo effect sizes for the primary outcomes ranged from 0.23 to 1.85, with a median of 0.64 (Fig.  2 ). Median heterogeneity across meta-analyses was I 2  = 72%, suggesting a generally high percentage of heterogeneity due to true variation across studies.

Dots represent placebo group effect size while triangles represent active effect size. CI confidence interval, MDD major depressive disorder, GAD generalized anxiety disorder, SAD social anxiety disorder, OCD obsessive-compulsive disorder, g Hedges’ g, d Cohen’s d, SMC standardized mean change, NR not reported.

A detailed description of each meta-analysis included for this objective is included in eResults. Here, we report a summary of these results in order of the greatest number of RCT’s and meta-analyses included per disorder. In MDD, a large within-group placebo effect was observed ( g  = 1.10, 95% CI [1.06, 1.15]), although active medication had an even larger effect size ( g  = 1.49, 95% CI [1.44, 1.53]) [ 50 ]. Similarly, in children and adolescents with MDD, placebo effect size was large ( g  = 1.57, 95% CI [1.36, 1.78]), as was serotonergic medication effect size ( g  = 1.85, 95% CI [1.70, 2.00]) [ 55 ]. In treatment-resistant MDD, the within-group placebo effect size was smaller than in non-treatment-resistant MDD ( g  = 0.89, 95% CI [0.81, 0.98]) [ 52 ]. In neuromodulation trials for MDD, the effect size of sham was g  = 0.80 (95% CI [0.65, 0.95]) [ 53 ]. In this meta-analysis, the effect size was larger for non-treatment-resistant ( g  = 1.28, 95% CI [0.47, 2.97]) compared to treatment-resistant participants (g = 0.50 95% CI [0.03, 0.99]) [ 53 ]. In adults with anxiety disorders, placebo effect sizes varied across disorders, with a medium effect size in panic disorder ( d  = 0.57, 95% CI [0.50, 0.64]) [ 56 ] and large effect sizes in generalized anxiety disorder (GAD) ( d  = 1.85, 95% CI [1.61, 2.09]) and social anxiety disorder (SAD) ( d  = 0.94, 95% CI [0.77, 1.12]) [ 57 ]. Other meta-analyses in children and adolescents and older adults pooled RCTs across anxiety disorders, and found large placebo effect sizes ( g  = 1.03, 95% CI [0.84, 1.21] and d  = 1.06, 95% CI [0.71, 1.42], respectively) [ 55 , 58 ]. In ADHD, placebo effect size was medium-to-large for clinician-rated outcomes (SMC = 0.75, 95% CI [0.67, 0.83]) [ 62 ]. There was additionally a significant negative relationship between placebo effect size and drug-placebo difference (−0.56, p  < 0.01) for self-rated outcomes [ 62 ]. In schizophrenia spectrum disorders, placebo effect size was small-to-medium in antipsychotic RCTs (SMC = 0.33, 95% CI [0.22, 0.44]) [ 38 ] and medium in RCTs focusing specifically on negative symptoms ( d  = 0.64, 95% CI [0.46, 0.83]) [ 60 ]. Placebo effect size in RLS was large when measured via rating scales ( g  = 1.41, 95% CI [1.25, 1.56]), but small ( g  = 0.02 to 0.24) in RCTs using objective outcomes [ 68 ]. In autism, placebo effect sizes were small (SMC ranged 0.23 to 0.36) [ 63 ]. Similarly, placebo effect size was small in OCD ( d  = 0.32, 95% CI [0.22, 0.41]), although larger in children and adolescents ( d  = 0.45, 95% CI [0.35, 0.56]) compared with adults ( d  = 0.27, 95% CI [0.15, 0.38]) [ 66 ]. Placebo effect size was large in AUD ( g  = 0.90, 95% CI [0.70, 1.09]) [ 61 ], small in primary insomnia ( g ranged 0.25 to 0.43) [ 67 ], and medium in intellectual disability related to genetic causes ( g  = 0.47, 95% CI [0.18, 0.76]) [ 65 ].

Our second objective was to examine the correlates of increased placebo response. We included 14 meta-analyses that reported correlates of placebo effect size or response rate through correlation analysis or meta-regression [ 38 , 51 , 53 , 54 , 56 , 57 , 59 , 60 , 61 , 62 , 63 , 64 , 66 , 68 ]. The key correlates extracted from these studies are summarized in Table  2 .

Several variables were consistently identified across meta-analyses. Increased number of trial sites was a positive correlate of increased placebo response in MDD [ 51 , 54 ], schizophrenia spectrum disorders [ 59 ], and autism spectrum disorders [ 63 ]. Similarly, increased sample size was positively associated with placebo effect size in schizophrenia spectrum disorders [ 59 ], OCD [ 66 ], and panic disorder [ 56 ]. Later publication or study year was associated with greater placebo response in anxiety disorders [ 56 , 57 ], schizophrenia spectrum disorders [ 38 ], AUD [ 61 ], and OCD [ 66 ] but not in MDD [ 51 ], and with reduced placebo response in ADHD [ 62 ]. Younger age was associated with increased placebo responses in schizophrenia spectrum disorders [ 38 , 59 ] and OCD [ 66 ]. Increased baseline illness severity was associated with increased placebo response in schizophrenia spectrum disorders [ 38 ], ADHD [ 62 ], and AUD [ 61 ]. Increased trial or follow-up duration was positively associated with increased placebo response in MDD [ 51 ], but negatively associated with placebo response in schizophrenia spectrum disorders [ 38 , 60 ] and OCD [ 66 ]. Finally, the effect size of active treatment was positively associated with increased placebo response in neurostimulation trials for MDD [ 53 ], bipolar depression [ 64 ], autistic spectrum disorders [ 63 ], and ADHD [ 62 ].

There were also some variables associated with increased placebo response in single disorders only. Flexible dosing, rather than fixed dosing, was associated with increased placebo response in MDD [ 51 ]. Increased illness duration was associated with reduced placebo response in schizophrenia spectrum disorders [ 38 ]. In RCTs for negative symptoms of schizophrenia, a higher number of active treatment arms was associated with increased placebo response [ 60 ]. A number of treatment administrations was a positive correlate of increased placebo response in patients with AUD [ 61 ]. A low risk of bias in selective reporting was associated with increased placebo response in ADHD [ 62 ]. Finally, a low risk of bias in allocation concealment was associated with increased placebo response in autism [ 63 ].

To our knowledge, this is the first overarching synthesis of the literature exploring the placebo response in RCTs of biological treatments across a broad range of mental disorders. We found that placebo responses were present and detectable across mental disorders. Further, the placebo effect size across these disorders varied between small and large (see Fig.  3 ). Additionally, several variables appeared to be associated with increased placebo effect size or response rate across a number of disorders, while others were reported for individual disorders only.

CI confidence interval, MDD major depressive disorder, GAD generalized anxiety disorder, SAD social anxiety disorder, OCD obsessive-compulsive disorder, g Hedges’ g, d Cohen’s d, SMC standardized mean change.

Our umbrella review distinguishes itself from a recent publication on placebo mechanisms across medical conditions [ 69 ]. Only four systematic reviews of research in mental disorders were included in that recent review [ 69 ], none of which were eligible for inclusion in our umbrella review, as we focus specifically on RCTs in mental disorders. Thus, our current umbrella review synthesizes different literature and is complementary [ 69 ].

We found substantial variation in placebo effect sizes across mental disorders. In GAD, SAD, MDD, AUD, and RLS (for subjective outcomes), placebo effects were large (>0.9), while they were small (approximately 0.3) in OCD, primary insomnia, autism, RLS (for objective outcomes), and schizophrenia spectrum disorders. It is noteworthy that placebo effect size/response rate correlated with active treatment effect size/response rate in many disorders (MDD, bipolar depression, ADHD, and autism). Nonetheless, where reported, active treatment was always superior. This possibly suggests an underlying ‘treatment responsiveness’ of these disorders that can vary in size. Perhaps, the natural history of a disorder is an important factor in ‘responsiveness’, i.e., disorders in which there is greater natural fluctuation in severity will show larger placebo (and active treatment) effect sizes. Supporting this hypothesis, increased trial duration predicted a larger placebo effect size in MDD, a disorder in which the natural course includes improvement [ 31 , 51 , 70 ]. Conversely, in schizophrenia spectrum disorders where improvement (particularly of negative symptoms) is less likely [ 71 ], increased trial and illness duration predicted a smaller placebo effect size [ 38 , 60 ]. However, previous meta-analyses suggest that natural improvement, for example, measured via waiting list control, does not fully account for the placebo effect in depression and anxiety disorders [ 72 , 73 ]. Statistical artifact, therefore, does not seem to fully explain the variation in effect size.

Non-specific treatment mechanisms are likely an additional source of the observed placebo effect. For example, those with treatment-resistant illness might have reduced expectations regarding treatment. This assumption is supported by the subgroup analysis reported by Razza and colleagues showing sham neuromodulation efficacy reduced as the number of previous failed antidepressant trials increased [ 53 ]. Another factor to consider is the outcome measure chosen. For example, the placebo effect size in panic disorder was smaller when calculated with objective or self-report measures compared with clinician-rated measures [ 56 ]. A similar finding was reported in ADHD trials [ 62 ]. Why placebo effect sizes would differ with clinician-rated versus self-rated scales is unclear. This might result from ‘demand characteristics’ (i.e., cues that suggest to a patient how they ‘should’ respond), or unblinding of the rater, or a combination of the two [ 74 , 75 ].

Several correlates of increased placebo response were reported in included meta-analyses. These included a larger sample size, more study sites, a later publication year (but with an opposite finding for ADHD), younger age, and increased baseline illness severity. This might reflect changes in clinical trial methods over time, the potential for increased ‘noise’ in the data with larger samples or more study sites, and, more speculatively, variables associated with increased volatility in symptoms [ 39 , 51 , 76 ]. A more extensive discussion regarding the potential reasons these variables might correlate with, or predict, placebo response is included in the eDiscussion. Although some correlates of increased placebo response were identified, perhaps more pertinently, it is unknown whether these also predict the separation between active treatment and placebo in most mental disorders. Three included meta-analyses did show that as placebo response increases, the likelihood of drug-placebo separation decreases [ 38 , 62 , 64 ]. This suggests correlates of placebo effect size are also correlates of trial success or failure, but this hypothesis needs explicit testing. In addition, few of the meta-analyses we included explored whether correlates of placebo response differed from correlates of active treatment response. For example, in clinical trials for gambling disorder, response to active treatment was predicted by weeks spent in the trial and by baseline severity, while response to placebo was predicted by baseline depressive and anxiety symptoms [ 77 ]. Furthermore, there is evidence that industry sponsorship is a specific correlate of reduced drug-placebo separation in schizophrenia spectrum disorders [ 78 ]. The largest meta-analysis that we included (conducted by Scott et al. [ 50 ]) did not explore correlates of increased placebo response through meta-regression analysis; rather, it was designed specifically to assess the impact of the use of placebo run-in periods in antidepressant trials. The authors found that use of a placebo run-in was associated with reduced placebo response. However, this effect did not enhance sensitivity to detect medication efficacy versus control groups, as trials with placebo run-in periods were also associated with a reduced medication response. Similar effects of placebo run-in were seen in univariate (but not multivariable) models in ADHD, where placebo run-in reduced placebo effect size in youth, but did not affect drug vs placebo difference [ 62 ]. Further work should be undertaken to ascertain whether trial-level correlates (including the use of placebo run-in) differentially explain active treatment or placebo response and whether controlling for these can improve drug-placebo separation.

Our results should be considered in the light of several possible limitations. First, as in any umbrella review, we were limited by the quality of the meta-analyses we included. Our AMSTAR-2 ratings suggest that confidence in the conclusions of most included meta-analyses should be critically low or low. Indeed, several meta-analyses did not assess for publication bias or for bias in included RCTs. This is relevant, as the risk of bias in selective reporting was highlighted as potentially being associated with placebo effect size in ADHD [ 62 ], and might therefore be relevant in other mental disorders. Second, our results are potentially vulnerable to biases or unmeasured confounders present in the included meta-analyses. Third, we attempted to prevent overlap and duplication of information by including only the meta-analyses with the most information. This might, however, have resulted in some data not being included in our synthesis. Fourth, an exploration of the potential clinical relevance of the placebo effect sizes reported here was outside the scope of the current review but should be considered an important question for future research. Finally, the meta-analyses we included encompassed RCTs with different levels of blinding (double-blind, single-blind). Although the majority of trials were likely double-blind, it is possible that different levels of blinding could have influenced placebo effect sizes through effects on expectations. Future analyses of placebo effects and their correlates should either focus on double-blind trials or compare results across levels of blinding. Related to this, the included meta-analyses pooled phase 2 and phase 3 trials (the latter of which will usually follow positive phase 2 trials), which might result in different expectation biases. Therefore, placebo effects should be compared between phase 2 and phase 3 trials in the future.

In this umbrella review, we found placebo effect sizes varied substantially across mental disorders. The sources of this variation remain unknown and require further study. Some variables were correlates of increased placebo response across mental disorders, including larger sample size, higher number of study sites, later publication year (opposite for ADHD), younger age, and increased baseline illness severity. There was also evidence that clinician-rated outcomes were associated with larger placebo effect sizes than self-rated or objective outcomes. We additionally identified important gaps in the literature, with no eligible systematic reviews identified in stress-related disorders, eating disorders, behavioural addictions, or bipolar mania. In relation to these disorders, some analyses have been published but they have not been included in systematic reviews/meta-analyses (e.g. analyses of individual patient data pooled across RCTs in acute mania [ 79 ] or gambling disorder [ 77 , 80 ]) and therefore were not eligible for inclusion here. We also focused on placebo response in RCTs of pharmacotherapies and neurostimulation interventions for mental disorders. We did not include placebo effects in psychosocial interventions, but such an analysis would also be valuable. Future studies should address these gaps in the literature and furthermore should compare findings in placebo arms with active treatment arms, both regarding treatment effect size and its correlates. Gaining additional insights into the placebo response may improve our ability to separate active treatment effects from placebo effects, thus paving the way for potentially effective new treatments for mental disorders.

Data availability

The datasets generated during and/or analysed during the current study are available in the Open Science Framework repository, https://osf.io/fxvn4/ .

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Acknowledgements

Dr Nathan TM Huneke is an NIHR Academic Clinical Lecturer. The views expressed in this publication are those of the author(s) and not necessarily those of the NIHR, NHS, or the UK Department of Health and Social Care. For the purpose of open access, the author has applied a Creative Commons Attribution License (CC BY) to any Author Accepted Manuscript version arising from this submission.

Author contributors

NTMH, JA, DSB, SRC, CUC, MG, CMH, RH, ODH, JMAS, MS, and SCo conceptualized the study. NTMH, AB, VB, LE, CJG, OKF, LM, CR, SS, and SCo contributed to data collection, data curation, or data analysis. NTMH, MS, and SCo wrote the first draft of the manuscript. All authors had access to the raw data. All authors reviewed and edited the manuscript and had final responsibility for the decision to submit it for publication.

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These authors contributed equally: Marco Solmi, Samuele Cortese.

Authors and Affiliations

Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK

Nathan T. M. Huneke, Jay Amin, David S. Baldwin, Samuel R. Chamberlain, Matthew Garner, Catherine M. Hill, Ruihua Hou, Konstantinos Ioannidis, Julia M. A. Sinclair & Samuele Cortese

Southern Health NHS Foundation Trust, Southampton, UK

Nathan T. M. Huneke, Jay Amin, David S. Baldwin, Samuel R. Chamberlain, Konstantinos Ioannidis & Satneet Singh

University Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa

David S. Baldwin

School of Psychology, University of Nottingham Malaysia, Semenyih, Malaysia

Alessio Bellato

Centre for Innovation in Mental Health, School of Psychology, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, UK

Alessio Bellato, Valerie Brandt, Matthew Garner, Corentin J. Gosling, Claire Reed, Marco Solmi & Samuele Cortese

Clinic of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, Hanover, Germany

Valerie Brandt

Department of Child and Adolescent Psychiatry, Charité Universitätsmedizin Berlin, Berlin, Germany

Christoph U. Correll

Department of Psychiatry, Zucker Hillside Hospital, Northwell Health, Glen Oaks, NY, USA

Department of Psychiatry and Molecular Medicine, Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, USA

Center for Psychiatric Neuroscience, Feinstein Institute for Medical Research, Manhasset, NY, USA

Faculty of Education and Psychology, University of Navarra, Pamplona, Spain

Luis Eudave

School of Psychology, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, UK

Matthew Garner

Université Paris Nanterre, DysCo Lab, F-92000, Nanterre, France

Corentin J. Gosling

Université de Paris, Laboratoire de Psychopathologie et Processus de Santé, F-92100, Boulogne-Billancourt, France

Department of Sleep Medicine, Southampton Children’s Hospital, Southampton, UK

Catherine M. Hill

Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, London, UK

Oliver D. Howes

H Lundbeck A/s, Iveco House, Watford, UK

Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK

Department of Clinical Medicine, Aarhus University, Aarhus, Denmark

Ole Köhler-Forsberg

Psychosis Research Unit, Aarhus University Hospital–Psychiatry, Aarhus, Denmark

Department of Translational Biomedicine and Neuroscience (DIBRAIN), University of Studies of Bari “Aldo Moro”, Bari, Italy

Lucia Marzulli

Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada

Marco Solmi

Department of Mental Health, Ottawa Hospital, Ottawa, ON, Canada

Ottawa Hospital Research Institute (OHRI) Clinical Epidemiology Program, University of Ottawa, Ottawa, ON, Canada

School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada

Solent NHS Trust, Southampton, UK

Samuele Cortese

DiMePRe-J-Department of Precision and Regenerative Medicine-Jonic Area, University “Aldo Moro”, Bari, Italy

Hassenfeld Children’s Hospital at NYU Langone, New York University Child Study Center, New York, NY, USA

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Correspondence to Nathan T. M. Huneke .

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Competing interests.

DSB is President of the British Association for Psychopharmacology, Editor of the Human Psychopharmacology journal (for which he receives an editor’s honorarium), and has received royalties from UpToDate. CMH has acted on an expert advisory board for Neurim Pharmaceuticals. ODH is a part-time employee and stockholder of Lundbeck A/s. He has received investigator-initiated research funding from and/or participated in advisory/speaker meetings organized by Angellini, Autifony, Biogen, Boehringer-Ingelheim, Eli Lilly, Heptares, Global Medical Education, Invicro, Jansenn, Lundbeck, Neurocrine, Otsuka, Sunovion, Recordati, Roche and Viatris/Mylan. ODH has a patent for the use of dopaminergic imaging. All other authors declare no competing interests. MS has received honoraria/has been a consultant for Angelini, Lundbeck, and Otsuka. SCo has received honoraria from non-profit associations (BAP, ACAMH, CADDRA) for educational activities and an honorarium from Medice. KI has received honoraria from Elsevier for editorial work. SRC receives honoraria from Elsevier for associate editor roles at comprehensive psychiatry and NBR journals. CUC has been a consultant and/or advisor to or has received honoraria from: AbbVie, Acadia, Adock Ingram, Alkermes, Allergan, Angelini, Aristo, Biogen, Boehringer-Ingelheim, Bristol-Meyers Squibb, Cardio Diagnostics, Cerevel, CNX Therapeutics, Compass Pathways, Darnitsa, Denovo, Gedeon Richter, Hikma, Holmusk, IntraCellular Therapies, Jamjoom Pharma, Janssen/J&J, Karuna, LB Pharma, Lundbeck, MedAvante-ProPhase, MedInCell, Merck, Mindpax, Mitsubishi Tanabe Pharma, Mylan, Neurocrine, Neurelis, Newron, Noven, Novo Nordisk, Otsuka, Pharmabrain, PPD Biotech, Recordati, Relmada, Reviva, Rovi, Sage, Seqirus, SK Life Science, Sumitomo Pharma America, Sunovion, Sun Pharma, Supernus, Takeda, Teva, Tolmar, Vertex, and Viatris. He provided expert testimony for Janssen and Otsuka. He served on a Data Safety Monitoring Board for Compass Pathways, Denovo, Lundbeck, Relmada, Reviva, Rovi, Supernus, and Teva. He has received grant support from Janssen and Takeda. He received royalties from UpToDate and is also a stock option holder of Cardio Diagnostics, Kuleon Biosciences, LB Pharma, Mindpax, and Quantic.

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PLACEBO EFFECTS IN RANDOMIZED TRIALS OF PHARMACOLOGICAL AND NEUROSTIMULATION INTERVENTIONS FOR MENTAL DISORDERS: AN UMBRELLA REVIEW SUPPLEMENTARY APPENDIX

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Huneke, N.T.M., Amin, J., Baldwin, D.S. et al. Placebo effects in randomized trials of pharmacological and neurostimulation interventions for mental disorders: An umbrella review. Mol Psychiatry (2024). https://doi.org/10.1038/s41380-024-02638-x

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Received : 01 February 2024

Revised : 17 June 2024

Accepted : 19 June 2024

Published : 24 June 2024

DOI : https://doi.org/10.1038/s41380-024-02638-x

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